KR102574219B1 - Variable-focus virtual image devices based on polarization conversion - Google Patents

Abstract

Exemplary display devices include a waveguide configured to propagate visible light under total internal reflection in a direction parallel to a major surface of the waveguide. The waveguide is formed with an outcoupling element configured to outcouple a portion of visible light in a direction perpendicular to a major surface of the waveguide. The exemplary display device additionally includes a polarization-selective notch reflector disposed on the first side of the waveguide and configured to transmit a portion of visible light having a second polarization while reflecting visible light having a first polarization. The exemplary display device further includes a polarization-independent notch reflector disposed on the second side of the waveguide and configured to reflect visible light having a first polarization and a second polarization, the polarization-independent notch reflector of visible light reflected therefrom. configured to convert polarization;

Description

VARIABLE-FOCUS VIRTUAL IMAGE DEVICES BASED ON POLARIZATION CONVERSION

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 62/462,850, filed February 23, 2017, entitled "VARIABLE-FOCUS VIRTUAL IMAGE DEVICES", which application claims in its entirety are incorporated herein by reference. This provisional patent application contains the following sections, all of which are incorporated by reference and form part of this patent application.

1. SECTION I: DESCRIPTION AND DRAWINGS FOR PART OF THE APPLICATION DESIGNED "DISPLAY SYSTEM WITH VARIABLE POWER REFLECTOR".

2. Section II: Specifications and drawings of part of the application entitled "VARIABLE-FOCUS VIRTUAL IMAGE DEVICES BASED ON POLARIZATION CONVERSION".

[0002] Sections I and II both discuss variable focus or variable power devices and features associated with the components of these devices, and both sections equally form part of the disclosure of this application. Accordingly, the various features, elements, structures, methods, etc. described in Section I may be used with, combined with, or combined with the features, elements, structures, methods, etc. described in Section II in any combination. , may be incorporated into them, or may be compatible with them in other ways. Likewise, the various features, elements, structures, methods, etc. described in Section II may be used with, combined with, or used with the features, elements, structures, methods, etc. described in Section I in any combination. , may be incorporated into them, or may be compatible with them in other ways.

[0003] This application also claims the following patent applications: US Application Serial No. 14/555,585, filed on November 27, 2014; US Application Serial No. 14/690,401, filed on April 18, 2015; US Application Serial No. 14/212,961, filed March 14, 2014; and U.S. Application Serial No. 14/331,218, filed on July 14, 2014, in their entireties, respectively.

[0004] The present disclosure relates to display systems, and more particularly to augmented reality display systems that include diffractive devices based at least in part on polarization conversion.

[0005] Modern computing and display technologies have facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which digitally reproduced images or portions of images do not appear or appear to be real. , is presented to the user in a way that can be perceived in practice. Virtual reality, or “VR” scenarios, typically involve the presentation of digital or virtual image information without transparency to other real-world visual input; Augmented reality, or "AR" scenarios, typically involve the presentation of digital or virtual image information as an augmentation to a visualization of the real world around the user. Mixed reality, or “MR” scenarios, are a type of AR scenario and typically involve virtual objects that are integrated into and respond to the natural world. For example, in an MR scenario, AR image content may be blocked by real-world objects or otherwise perceived as interacting with real-world objects.

[0006] Referring to FIG. 1 , an augmented reality scene 1 is shown, where a user of AR technology sees a real world featuring people, trees, buildings, and a concrete platform 1120 in the background. View park-type setting 1100. In addition to these items, the user of the AR technology may also add content such as a robot statue 1110 standing on a real-world platform 1120, and a flying cartoon-like avatar that appears to be an anthropomorphism of a bumblebee. Although it perceives “seeing” the character 1130, these elements 1130 and 1110 do not exist in the real world. Because the human visual perception system is complex, creating AR technology that facilitates comfortable, natural, and rich presentation of virtual imagery elements among other virtual or real-world imagery elements is challenging.

[0007] The systems and methods disclosed herein address various challenges related to AR and VR technology.

[0008] This application includes a discussion of systems and methods that can be used to provide variable optical power. Variable focus or variable power devices may find application in certain head mounted display devices that project images as if they originated at different depths. By changing the optical power of an optical element in a head mounted display device, images presented to a wearer of the head mounted display device appear to be located at different distances from the wearer. Thus, a variable focus or variable power optical device can be modulated such that different image content is displayed as if the image content were located at different positions relative to the user. Some variable power elements include reflectors that include movable membranes. Other variable power elements include liquid crystal switchable devices that can switch between optical power levels using switchable liquid crystal elements. Some variable focus devices described herein utilize polarization properties of light to facilitate switching from one focal point to another.

[0009] In one aspect, a display device includes a waveguide configured to propagate visible light under total internal reflection in a direction parallel to a major surface of the waveguide; and an outcoupling element formed on the waveguide and configured to outcouple a portion of visible light in a direction perpendicular to a major surface of the waveguide. The display device additionally includes a polarization-selective notch reflector disposed on the first side of the waveguide and configured to transmit a portion of visible light having a second polarization while reflecting visible light having a first polarization. The display device further includes a polarization-independent notch reflector disposed on the second side of the waveguide and configured to reflect visible light having a first polarization and a second polarization, wherein the polarization-independent notch reflector determines the polarization of visible light reflected therefrom. configured to convert

[0010] In another aspect, a display device includes a wave-guiding device interposed between a first switchable lens and a second switchable lens, wherein the wave-guiding device has a plurality of chiral structures. ), wherein each chiral structure extends in a layer depth direction and includes a plurality of liquid crystal molecules continuously rotated in a first rotation direction, and liquid crystals of chiral structures The arrangements of the molecules are periodically fluctuated laterally perpendicular to the layer depth direction, causing one or more CLC layers to be configured to Bragg-reflect incident light. The light-guide device is additionally formed over the one or more CLC layers and propagates visible light under total internal reflection (TIR) in a direction parallel to the major surface of the waveguide and optically couples visible light to or from the one or more CLC layers. It includes one or more waveguides configured to ring.

[0011] In another aspect, a display device configured to display an image to an eye of a user includes an optical display. The optical display has a front side and a back side, the back side being closer to the user's eyes than the front side. The optical display is configured to output light having a wavelength range towards the rear side. A first notch reflector is disposed behind the optical display, and the first notch reflector is configured to reflect light having a range of wavelengths output from the optical display. A second notch reflector is disposed in front of the optical display, and the second notch reflector is configured to reflect light having a range of wavelengths. The first notch reflector is configured to substantially transmit light having a first polarization and substantially reflect light having a second polarization different from the first polarization. The second notch reflector is configured to convert light incident on the back face, having a second polarization, to a first polarization and redirect the light backward.

[0012] In another aspect, a dynamically focused display system includes a display configured to output circularly polarized light in a first circular polarization state. The display is disposed along an optical axis and has an anterior side and a posterior side, the posterior side closer to the user's eyes than the anterior side, and the optical display is configured to output light having a range of wavelengths toward the posterior side. A first switchable optical element is disposed along the optical axis, the first switchable optical element converts a circular polarization state of light transmitted through the first switchable optical element from the first circular polarization state to a second, different circular polarization state. It is configured to change to A first cholesteric liquid crystal (CLC) lens is disposed in front of the first switchable optical element along an optical axis. A second switchable optical element is disposed in front of the first CLC lens along an optical axis, and the second switchable optical element converts a circular polarization state of light transmitted through the second switchable optical element from the first circular polarization state. and change to a second, different circular polarization state. A second CLC lens is disposed in front of the second switchable optical element along the optical axis. The controller is configured to electronically switch states of the first and second switchable optical elements to dynamically select the first CLC lens or the second CLC lens.

[0013] In another aspect, a wearable augmented reality head-mounted display system is configured to direct light from the world in front of a wearer wearing the head-mounted system to the eyes of the wearer. A wearable augmented reality head-mounted display system includes an optical display configured to output light to form an image; one or more waveguides positioned to receive the light from the display; a frame configured to place waveguides in front of the eye such that the one or more waveguides have an anterior side and a posterior side, the posterior side being closer to the eye than the anterior side; a cholesteric liquid crystal (CLC) reflector disposed on the front side of the one or more waveguides, wherein the CLC reflector is configured to have an adjustable optical power or depth of focus upon application of an electrical signal; and one or more out-coupling elements disposed relative to the one or more waveguides for extracting light from the one or more waveguides and directing at least a portion of the light propagating within the waveguide to a CLC reflector, the light comprising: It is directed from the CLC reflector back through the waveguide and to the eye to present an image from the display to the eye of the wearer.

[0014] In another aspect, a display device includes a waveguide configured to propagate visible light under total internal reflection in a direction parallel to a major surface of the waveguide and outcouple visible light in a direction perpendicular to the major surface. The notch reflector is configured to reflect visible light having a first polarization, the notch reflector includes one or more cholesteric liquid crystal (CLC) layers, each of the CLC layers includes a plurality of chiral structures, each of the chiral structures has a layer depth. direction and continuously rotated in the first rotation direction, the arrangements of the liquid crystal molecules of chiral structures are periodically fluctuated in the lateral direction perpendicular to the layer depth direction, so that one or more CLC layers reflect incident light. Make it Bragg-reflect.

[0015] Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and description below. Other features, aspects, and advantages will be apparent from the description, drawings, and claims. Neither this summary nor the detailed description that follows is intended to limit or limit the scope of the claimed subject matter of the present invention.

[0016] FIG. 1 illustrates a user's view of AR through an augmented reality (AR) device.
2 illustrates an example of a wearable display system.
[0018] FIG. 3 illustrates a conventional display system for simulating three-dimensional imagery for a user.
[0019] FIG. 4 illustrates aspects of an approach for simulating three-dimensional imagery using multiple depth planes.
[0020] FIGS. 5A-5C illustrate relationships between radius of curvature and radius of focus.
6 illustrates an example of a waveguide stack for outputting image information to a user.
7 illustrates an example of outgoing beams output by a waveguide.
[0023] FIG. 8 illustrates an example of a stacked waveguide assembly including images where each depth plane is formed using a number of different component colors.
[0024] FIG. 9A illustrates a cross-sectional side view of an example of a set of stacked waveguides each including an incoupling optical element.
[0025] FIG. 9B illustrates a perspective view of the example of the plurality of stacked waveguides of FIG. 9A.
[0026] FIG. 9C illustrates a top-down plan view of the example of the plurality of stacked waveguides of FIGS. 9A and 9B.
10 illustrates a cross-sectional side view of an example of a cholesteric liquid crystal diffraction grating (CLCG) having a plurality of uniform chiral structures.
[0028] FIG. 11 illustrates a cross-sectional side view of an example of a CLCG having chiral structures arranged differently in the lateral direction.
[0029] FIG. 12 illustrates a cross-sectional side view of an example of a CLC layer configured for Bragg-reflection at an off-axis angle of incidence.
[0030] FIG. 13A illustrates a cross-sectional side view of an example of a CLC layer configured for Bragg-reflection at a first off-axis angle of incidence and having a first helical pitch.
[0031] FIG. 13B illustrates a cross-sectional side view of an example of a CLC layer configured for Bragg-reflection at a second off-axis angle of incidence and having a second helical pitch.
[0032] FIG. 13C is an example side view of a CLCG comprising the CLC layers of FIGS. 13A and 13B, with different helical pitches in a stacked configuration, for Bragg-reflection at multiple off-axis angles of incidence and high diffraction bandwidth. Illustrate the cross section.
[0033] FIG. 14 illustrates a cross-sectional side view of an example of a CLCG comprising a CLC layer having vertical zones with multiple off-axis angles of incidence and different helical pitches along the depth direction for Bragg-reflection at high diffraction bandwidth. .
[0034] FIG. 15 illustrates a cross-sectional side view of an example of a CLCG comprising a CLC layer having lateral zones with different helical pitches along the lateral direction for spatially varied Bragg-reflection.
[0035] FIG. 16 illustrates an example of an optical light waveguide device that includes a waveguide coupled to a CLCG and configured to propagate light by total internal reflection (TIR).
[0036] FIG. 17A illustrates an example of an optical light waveguide device including a waveguide coupled to a CLCG and configured to selectively propagate light having a wavelength by total internal reflection (TIR).
[0037] FIG. 17B illustrates an example of a plurality of optical light waveguide devices of the same optical path, each comprising a waveguide coupled to a CLCG and configured to selectively propagate light having a wavelength by total internal reflection (TIR) do.
[0038] FIG. 17C illustrates an example of a plurality of optical light waveguide devices of the same optical path, each including a waveguide coupled to a CLCG and configured to selectively propagate light having a wavelength by total internal reflection (TIR) do.
[0039] FIG. 18 illustrates an example of an optical lightguide device including a common waveguide coupled to a plurality of CLCGs and configured to selectively propagate light having a plurality of wavelengths by total internal reflection (TIR).
[0040] FIG. 19 illustrates an example of an optical light waveguide device that includes a waveguide coupled to a CLCG and configured to propagate light by total internal reflection (TIR).
[0041] FIG. 20 illustrates an example of an optical light waveguide device comprising a polarization converting reflector and a waveguide coupled to a CLCG, where the CLCG is configured to receive incident light, and the waveguide is configured to transmit light to the CLCG by total internal reflection (TIR). configured to propagate Bragg-reflected light from
[0042] FIG. 21A illustrates the optical light waveguide device of FIG. 20, where the CLCG is configured to receive incident light, either linearly polarized or unpolarized, and the waveguide comprises Bragg-reflected light from the CLCG and total internal reflection (TIR). ) to propagate the light reflected by the reflector.
[0043] FIG. 21B illustrates the optical light waveguide device of FIG. 20, where the CLCG is configured to receive incident light that is polarized into orthogonal elliptical or circularly polarized light beams and the waveguide includes the Bragg-reflected light from the CLCG and the TIR ( It is configured to propagate light reflected by the reflector with total internal reflection.
[0044] FIG. 22A shows a first CLC layer having chiral structures with a first rotation direction and a chiral structure with a second rotation direction opposite to the first rotation direction, under conditions where an incident light beam is linearly polarized or unpolarized. An example of an optical light guide device including a plurality of CLC layers coupled to a common waveguide, including a second CLC layer having .
[0045] FIG. 22B illustrates the optical light waveguide device of FIG. 22A under the condition that incident light is polarized into orthogonal elliptical or circularly polarized light beams.
[0046] FIG. 22C shows a first CLC layer having chiral structures with a first rotation direction and a chiral structure with a second rotation direction opposite to the first rotation direction, under conditions where an incident light beam is linearly polarized or unpolarized. An example of an optical light guide device including a plurality of CLC layers coupled to a common waveguide interposed between two CLC layers, including a second CLC layer having .
[0047] FIG. 23 illustrates an example of an imaging system that includes a front-facing camera configured to image a wearer's eye using a cholesteric liquid crystal (CLC) off-axis mirror.
[0048] FIGS. 24A-24F illustrate an example of an imaging system that includes a front-facing camera configured to image a wearer's eye using a CLC off-axis mirror.
[0049] FIGS. 24G and 24H are imaging the eye of a wearer using a diffractive optical element comprising a plurality of segments (each of which may have different optical properties) comprising one or more CLC off-axis mirrors. Examples of imaging systems that include a forward-facing camera configured to
[0050] FIG. 25A illustrates an example display device that includes a polarization converter and is configured to output an image to a user.
[0051] FIG. 25B illustrates an example display device that includes a polarization converter and is configured to output an image to a user.
[0052] FIG. 26A illustrates an example display device comprising a polarization converter and a switchable lens and configured to output a virtual image to a user.
[0053] FIG. 26B illustrates an example display device comprising a polarization converter and a switchable lens and configured to output a real image to a user.
[0054] FIG. 26C illustrates an example display device comprising a polarization converter and a switchable lens and configured to output a virtual image to a user.
[0055] FIG. 26D illustrates an example display device comprising a polarization converter and a switchable lens and configured to output a real image to a user.
[0056] FIG. 27A illustrates an example display device comprising a polarization converter and a Pancharatnam-Barry (PB) lens and configured to output a virtual image to a user.
[0057] FIG. 27B illustrates an example display device including a polarization converter and a PB lens and configured to output a real image to a user.
[0058] FIG. 27C illustrates an example display device comprising a polarization converter and a PB lens and configured to output a virtual image to a user.
[0059] FIG. 27D illustrates an example display device including a polarization converter and a PB lens and configured to output a real image to a user.
[0060] FIG. 28A illustrates a spatial offset created by two orthogonally polarized images formed by an example display device that includes a polarization converter and a PB lens.
[0061] FIG. 28B illustrates an example offset compensator comprising a pair of lenses for compensating for the spatial offset illustrated in FIG. 28A.
[0062] FIG. 28C illustrates the effect of nulling the spatial offset illustrated in FIG. 28A using the embodiment of the offset compensator illustrated in FIG. 28B.
[0063] FIG. 29 illustrates an example display device comprising a PB lens and a waveguide assembly configured to project light asymmetrically and configured to output an image to a user.
[0064] FIG. 30 illustrates an example display device comprising a CLCG and a waveguide assembly having a deformable mirror and configured to output an image to a user.
[0065] FIGS. 31A-31C illustrate example reflective diffractive lenses that can be implemented as part of a display device, where the reflective diffractive lenses are formed from patterned CLC materials that serve as a reflective polarizing mirror.
[0066] FIG. 32A illustrates an example of chromatic aberration observed in diffractive lenses.
[0067] FIG. 32B illustrates an example reflective diffractive lens comprising a plurality of reflective diffractive lenses in a stacked configuration.
[0068] Figures 33A-33D illustrate example reflective diffractive lens assemblies and their operation for dynamic switching between different focal lengths.
[0069] FIG. 34 illustrates an example combination of a waveguide assembly comprising an eyepiece configured to direct light towards the world and a CLC lens configured to redirect light towards the eye.
[0014] Throughout the drawings, reference numbers may be reused to indicate correspondence between referenced elements. The drawings are provided to illustrate exemplary embodiments described herein and are not intended to limit the scope of the present disclosure.

[0070] AR systems can display virtual content to a user or viewer while allowing the user to continue seeing the world around them. Preferably, this content is displayed on a head-mounted display that projects image information to the user's eyes, eg, as part of eyewear. Additionally, the display may also transmit light from the surrounding environment to the user's eyes to allow viewing of the surrounding environment. As used herein, it will be appreciated that a “head-mounted” display is a display that can be mounted on a viewer's head.

2 illustrates an example of a wearable display system 80 . The display system 80 includes a display 62 and various mechanical and electronic modules and systems to support the functions of the display 62 . The display 62 may be coupled to a frame 64 that is wearable by a display system user or viewer 60 and configured to position the display 62 in front of the eyes of the user 60 . Display 62 may be considered eyewear in some embodiments. In some embodiments, speaker 66 is coupled to frame 64 and positioned adjacent to the ear canal of user 60 (in some embodiments, another speaker, not shown, is positioned adjacent to another ear canal of user 60). positioned to provide stereo/shapeable sound control). In some embodiments, the display system may also include one or more microphones 67 or other devices for detecting sound. In some embodiments, the microphone is configured to allow a user to provide inputs or commands to system 80 (eg, selection of spoken menu commands, natural language questions, etc.), and/or other people (eg, similar other users of the display systems). The microphone may also be configured as an ambient sensor to continuously collect audio data (eg, passively from the user and/or environment). Such audio data may include user sounds, such as heavy breathing, or environmental sounds, such as a loud bang indicating a nearby event. The display system may also include a perimeter sensor 30a that is separate from the frame 64 and may be attached to the body of the user 60 (eg, the head, torso, extremity, etc., of the user 60). there is. Ambient sensor 30a may, in some embodiments, be configured to acquire data characterizing a physiological state of user 60, as further described herein. For example, the sensor 30a may be an electrode.

[0072] With continued reference to FIG. 2, display 62 may be mounted in a variety of configurations, e.g., fixedly attached to frame 64, fixedly attached to a helmet or hat worn by a user, or , a communication link (eg, in a backpack-style configuration, in a belt-coupling style configuration) to a local data processing module 70 that is embedded in the headphones or otherwise removably attached to the user 60 (eg, in a backpack-style configuration, in a belt-coupling style configuration). 68), eg by wired leads or wireless connectivity. Similarly, sensor 30a may be operatively coupled to local processor and data module 70 by a communication link 30b, eg, a wired lead or wireless connectivity. Local processing and data module 70 may include a hardware processor as well as digital memory, such as non-volatile memory (eg, flash memory or hard disk drives), both of which may include processing, caching, and processing of data. ) and storage. The data may be a) sensors (e.g., which may be operatively coupled to frame 64 or otherwise attached to user 60), e.g., image capture devices (e.g., cameras), microphones, inertial measurements. units, accelerometers, compasses, GPS units, radio devices, gyros and/or other sensors disclosed herein; and/or b) acquired and/or processed using remote processing module 72 and/or remote data repository 74 (including data related to virtual content) (possibly such processing or retrieval). data for delivery to the display 62 after retrieval. Local processing and data module 70 may be operably coupled to remote processing module 72 and remote data repository 74 by communication links 76 and 78, e.g., via wired or wireless communication links. , so that these remote modules 72 and 74 are operably coupled to each other and available as resources for the local processing and data module 70 . In some embodiments, local processing and data module 70 may use one or more of image capture devices, microphones, inertial measurement units, accelerometers, compasses, GPS units, radio devices, and/or gyros. can include In some other embodiments, one or more of these sensors may be attached to frame 64 or may be standalone structures that communicate with local processing and data module 70 by wired or wireless communication channels.

[0073] With continued reference to FIG. 2, in some embodiments, remote processing module 72 may include one or more processors configured to analyze and process data and/or image information. In some embodiments, remote data repository 74 may include digital data storage facilities that may be available over the Internet or other networking arrangements in a “cloud” resource configuration. In some embodiments, remote data repository 74 provides one or more remote servers that provide information, eg, information for generating augmented reality content, to local processing and data module 70 and/or remote processing module 72. may include In some embodiments, all data is stored and all computations are performed in the local processing and data module, allowing fully autonomous use from the remote module.

[0074] The perception of an image as being "three-dimensional" or "3-D" may be achieved by presenting slightly different presentations of the image to each eye of a viewer. 3 illustrates a conventional display system for simulating three-dimensional imagery for a user. Two separate images 5 and 7 (one for each eye 4 and 6) are output to the user. Images 5 and 7 are spaced from eyes 4 and 6 by a distance 10 along the optical or z-axis parallel to the viewer's line of sight. Images 5 and 7 are flat, and eyes 4 and 6 can be focused on the images by assuming a single accommodating state. Such systems rely on the human visual system to combine images 5 and 7 to provide a perception of scale and/or depth to the combined image.

[0075] However, it will be appreciated that the human visual system is more complex and more difficult to provide realistic depth perception. For example, many viewers of conventional 3-D display systems find such systems uncomfortable, or may not perceive depth at all. Without being limited by theory, it is believed that viewers of an object may perceive the object as being three-dimensional due to a combination of disjunction and accommodation. The vergence movements of the two eyes relative to each other (i.e., the rotation of the eyes to move the pupils towards or away from each other to converge their gazes to gaze at an object) are the movements of the pupils of the eyes and the lens It is closely related to their focusing (or accommodation). Under normal conditions, changing the focus of the lenses of the eyes, or accommodating the eyes, to change focus from one object to another at a different distance, is known as the "accommodation-vergence reflex". Under a relationship known as “reflex”, matching changes in disjunctive motion over the same distance will automatically cause pupillary dilation and constriction as well. Likewise, a change in vergence will trigger a matching change in accommodation, of lens shape and pupil size, under normal conditions. As referred to herein, a number of stereoscopic or “3-D” display systems provide slightly different presentations (and thus slightly different images) to each eye such that a three-dimensional perspective is perceived by the human visual system. ) to display the scene. However, such systems are inconvenient for many viewers because, among other things, such systems simply provide a different presentation of a scene, but the eyes see all image information in a single accommodation, and "accommodation- This is because it works against the disjunctive reflex. Display systems that provide better matching between accommodation and displacement will create more realistic and comfortable simulations of three-dimensional imagery, contributing to increased wearing duration and, consequently, adherence to diagnostic and treatment protocols. can

4 illustrates aspects of an approach for simulating 3-dimensional imagery using multiple depth planes. Referring to FIG. 4 , objects at various distances from eyes 4 and 6 on the z-axis are accommodated by eyes 4 and 6 such that these objects are in focus. Eyes 4 and 6 assume certain accommodation conditions that allow them to focus on objects at different distances along the z-axis. Consequently, a particular accommodation state can be said to be associated with a particular one of the depth planes 14, with an associated focal length, such that objects or parts of objects in a particular depth plane are Focusing is correct when you are accommodating to that depth plane. In some embodiments, three-dimensional imagery can be simulated by providing different presentations of an image to each of the eyes 4, 6, and also by providing different presentations of an image corresponding to each of the depth planes. there is. Although shown as separate for clarity of illustration, it will be appreciated that the fields of view of eyes 4 and 6 may overlap, eg, as distance along the z-axis increases. Additionally, while shown as flat for ease of illustration, it will be appreciated that the contours of the depth plane can be curved in physical space, so that all features of the depth plane come into focus with the eye in a particular accommodation state.

[0077] The distance between the object and the eye 4 or 6 may also change the amount of divergence of light from the object when viewed with that eye. 5A-5C illustrate the relationships between distance and divergence of rays. The distance between the object and the eye 4 is represented by R1, R2 and R3 in order of decreasing distance. As shown in Figures 5a-5c, the rays diverge more as the distance to the object decreases. As the distance increases, the rays become more collimated. In other words, the light field created by a point (object or part of an object) can be said to have a spherical wavefront curvature, which is a function of how far the point is from the user's eye. The curvature increases as the distance between the object and the eye 4 decreases. As a result, at different depth planes, the degree of divergence of the rays is also different, and the degree of divergence increases as the distance between the depth planes and the viewer's eye 4 decreases. Although only one eye 4 is illustrated for clarity of illustration in FIGS. 5A-5C and other figures herein, it should be noted that discussions of eye 4 may apply to both eyes 4 and 6 of the viewer. will be recognized

[0078] Without being limited by theory, it is believed that the human eye can typically interpret a finite number of depth planes to provide depth perception. Consequently, a highly plausible simulation of perceived depth can be achieved by presenting to the eye different presentations of an image corresponding to each of these limited number of depth planes. Different presentations may be separately focused by the viewer's eyes, thus based on eye accommodation required to focus on different image features for a scene located on different depth planes and/or Helps provide depth clues to the user based on observing that different image features on different depth planes are out of focus.

6 illustrates an example of a waveguide stack for outputting image information to a user. Display system 1000 is a stack of waveguides, or a stacked waveguide assembly ( 1178). In some embodiments, display system 1000 is system 80 of FIG. 2 , and FIG. 6 schematically shows some portions of system 80 in more detail. For example, waveguide assembly 1178 may be part of display 62 of FIG. 2 . It will be appreciated that display system 1000 may be considered a light field display in some embodiments.

[0080] With continued reference to FIG. 6, the waveguide assembly 1178 may also include a plurality of features 1198, 1196, 1194, 1192 between the waveguides. In some embodiments, features 1198, 1196, 1194, and 1192 may be one or more lenses. Waveguides 1182, 1184, 1186, 1188, 1190 and/or plurality of lenses 1198, 1196, 1194, 1192 may be configured to transmit image information to the eye at various levels of wavefront curvature or ray divergence. . Each waveguide level can be associated with a particular depth plane and configured to output image information corresponding to that depth plane. Image injection devices 1200, 1202, 1204, 1206, 1208 can function as a source of light for the waveguides and will be utilized to inject image information into the waveguides 1182, 1184, 1186, 1188, 1190. and each of the waveguides may be configured to distribute the incoming light across each individual waveguide for output towards the eye 4, as described herein. The light exits the output surfaces 1300, 1302, 1304, 1306, 1308 of the image injection devices 1200, 1202, 1204, 1206, 1208 and enters the corresponding inputs of the waveguides 1182, 1184, 1186, 1188, 1190. Surfaces 1382, 1384, 1386, 1388, and 1390 are implanted. In some embodiments, each of input surfaces 1382, 1384, 1386, 1388, 1390 can be an edge of a corresponding waveguide, or can be part of a major surface of a corresponding waveguide (i.e., one of the waveguide surfaces is directly facing the world 1144 or the viewer's eye 4). In some embodiments, a single light beam (eg, a collimated beam) is a cloned collimated beam directed toward the eye 4 at particular angles (and amounts of divergence) corresponding to a depth plane associated with a particular waveguide. collimated beams) may be injected into each waveguide to output a full field. In some embodiments, only one of the image implantation devices 1200, 1202, 1204, 1206, 1208 is a plurality of (eg, three) waveguides 1182, 1184, 1186, 1188, 1190 It is associated with and can inject light into it.

[0081] In some embodiments, image injection devices (1200, 1202, 1204, 1206, 1208) respectively generate image information for implantation into a corresponding waveguide (1182, 1184, 1186, 1188, 1190). These are discrete displays. In some other embodiments, the image injection devices 1200, 1202, 1204, 1206, 1208 transmit image information through one or more optical conduits (eg, fiber optic cables) to the image injection devices 1200, 1202, for example. , 1204, 1206, 1208) are the output ends of a single multiplexed display that can be piped to each. It should be noted that image information provided by image injection devices 1200, 1202, 1204, 1206, 1208 may include light of different wavelengths or colors (eg, different component colors as discussed herein). will be recognized

[0082] In some embodiments, light injected into waveguides 1182, 1184, 1186, 1188, 1190 includes light module 2040, which may include a light emitter such as a light emitting diode (LED). is provided by the light projector system 2000. Light from light module 2040 may be directed through beam splitter 2050 to light modulator 2030, eg, spatial light modulator, and modified by it. Light modulator 2030 may be configured to change the perceived intensity of light injected into waveguides 1182 , 1184 , 1186 , 1188 , 1190 . Examples of spatial light modulators include liquid crystal displays (LCDs) including liquid crystal on silicon (LCOS) displays.

[0083] In some embodiments, display system 1000 directs light in various patterns (eg, raster scan, spiral scan, Lissajous pattern, etc.) to one or more waveguides 1182, 1184, 1186, 1188. , 1190) and ultimately into the eye 4 of a viewer, a scanning fiber display comprising one or more scanning fibers configured to project. In some embodiments, the illustrated image injection devices 1200, 1202, 1204, 1206, 1208 are a single scanning fiber configured to inject light into one or plurality of waveguides 1182, 1184, 1186, 1188, 1190. Alternatively, bundles of scanning fibers may be schematically represented. In some other embodiments, the illustrated image injection devices 1200, 1202, 1204, 1206, 1208 schematically represent a plurality of scanning fibers or a plurality of bundles of scanning fibers, each of which has waveguides 1182 , 1184, 1186, 1188, 1190) into the associated one. It will be appreciated that one or more optical fibers may be configured to transmit light from optical module 2040 to one or more waveguides 1182 , 1184 , 1186 , 1188 , 1190 . For example, a scanning fiber or fibers and one or more waveguides (1182, 1184, 1186, 1188, 1190) to redirect light exiting the scanning fiber to one or more waveguides (1182, 1184, 1186, 1188, 1190). It will be appreciated that one or more intervening optical structures may be provided.

[0084] Controller 1210 controls one or more waveguides of stacked waveguide assembly 1178, including operation of image injection devices 1200, 1202, 1204, 1206, 1208, light source 2040 and light modulator 2030. control their actions. In some embodiments, controller 1210 is part of local data processing module 70 . Controller 1210 may program (e.g., non-transiently instructions of the medium). In some embodiments, the controller may be a single integrated device or a distributed system connected by wired or wireless communication channels. Controller 1210 may be part of processing modules 70 or 72 (FIG. 1) in some embodiments.

[0085] With continued reference to FIG. 6, waveguides 1182, 1184, 1186, 1188, and 1190 may be configured to propagate light within each individual waveguide by total internal reflection (TIR). Waveguides 1182, 1184, 1186, 1188, 1190 may each be planar or have another shape (eg, curved), and have major top and bottom surfaces and edges extending between these major top and bottom surfaces. . In the illustrated configuration, the waveguides 1182, 1184, 1186, 1188 and 1190 are configured to extract light out of the waveguide by redirecting light propagating within each individual waveguide out of the waveguide to output image information to the eye 4. configured outcoupling optical elements 1282, 1284, 1286, 1288, and 1290, respectively. The extracted light may also be referred to as outcoupled light, and the outcoupling optical elements may also be referred to as light extraction optical elements. The extracted light beam is output by the waveguide at locations where light propagating within the waveguide strikes the light extraction optical element. Outcoupling optical elements 1282, 1284, 1286, 1288, 1290 may be gratings that include diffractive optical features, eg, as discussed further herein. Although illustrated as being disposed on the lowermost major surfaces of waveguides 1182, 1184, 1186, 1188, and 1190 for ease of explanation and clarity of drawing, in some embodiments, outcoupling optical elements 1282, 1284, 1286, 1288, 1290) may be disposed on the top and/or bottom major surfaces and/or directly in the volume of waveguides 1182, 1184, 1186, 1188, 1190, as further discussed herein. can be placed. In some embodiments, outcoupling optical elements 1282, 1284, 1286, 1288, 1290 are formed in a material layer attached to a transparent substrate to form waveguides 1182, 1184, 1186, 1188, 1190. It can be. In some other embodiments, waveguides 1182, 1184, 1186, 1188, 1190 may be a monolithic piece of material and outcoupling optical elements 1282, 1284, 1286, 1288, 1290 The silver may be formed on and/or within the surface of that piece of material.

[0086] With continued reference to FIG. 6, and as discussed herein, each waveguide 1182, 1184, 1186, 1188, 1190 is configured to output light to form an image corresponding to a particular depth plane. For example, the waveguide 1182 closest to the eye may be configured to deliver collimated light injected into the waveguide 1182 to the eye 4 . The collimated light may represent an optical infinity focal plane. The next waveguide 1184 above can be configured to direct the collimated light through the first lens 1192 (eg, negative lens) before the collimated light can reach the eye 4; Such a first lens 1192 can be configured to produce a slightly convex wavefront curvature such that the eye/brain directs light coming from the next waveguide 1184 above, closer inward from optical infinity towards the eye 4 . 1 interpreted as coming from the focal plane. Similarly, the above third waveguide 1186 passes its output light through both the first 1192 and second 1194 lenses before reaching the eye 4; The combined optical power of the first (1192) and second (1194) lenses can be configured to produce different incremental amounts of wavefront curvature, such that the eye/brain can detect light coming from the third waveguide (1186). , interpret it as coming from the second focal plane much closer inward toward the person from optical infinity than the light from the next waveguide 1184 above.

[0087] The other waveguide layers 1188, 1190 and lenses 1196, 1198 are similarly configured, with the highest waveguide 1190 in the stack an aggregate representing its output, the focal plane closest to the person. It transmits the focal power through both the lenses between itself and the eye. To compensate for the stack of lenses 1198, 1196, 1194, 1192 when viewing/interpreting light coming from the world 1144 on the other side of the stacked waveguide assembly 1178, the compensating lens layer 1180 is may be placed at the top of the stack to compensate for the aggregate power of the lens stacks 1198, 1196, 1194, and 1192. This configuration provides as many perceived focal planes as there are available waveguide/lens pairs. Both the outcoupling optical elements of the waveguides and the focusing aspects of the lenses may be static (ie neither dynamic nor electro-active). In some alternative embodiments, either or both may be dynamic using electro-active features.

[0088] In some embodiments, two or more of waveguides 1182, 1184, 1186, 1188, 1190 may have the same associated depth plane. For example, multiple waveguides 1182, 1184, 1186, 1188, 1190 can be configured to output images set to the same depth plane, or multiple waveguides 1182, 1184, 1186, 1188, 1190 Subsets can be configured to output images set to the same plurality of depth planes (one image set for each depth plane). This may provide the advantages of forming a tiled image to provide an expanded field of view at such depth planes.

[0089] With continued reference to FIG. 6, outcoupling optical elements 1282, 1284, 1286, 1288, 1290 redirect light out of their respective waveguides and also by the appropriate amount for a particular depth plane associated with the waveguide. It may be configured to output this light with divergence or collimation of . As a result, waveguides with different associated depth planes can have different configurations of outcoupling optical elements 1282, 1284, 1286, 1288, 1290, which outcoupling optical elements have different amounts depending on the associated depth plane. Light is output by divergence of In some embodiments, light extraction optical elements 1282, 1284, 1286, 1288, 1290 can be volumetric or surface features that can be configured to output light at specific angles. For example, light extraction optical elements 1282, 1284, 1286, 1288, 1290 may be volume holograms, surface holograms, and/or diffraction gratings. In some embodiments, features 1198, 1196, 1194, and 1192 may not be lenses; Rather, they may simply be spacers (eg, cladding layers and/or structures for forming air gaps).

[0090] In some embodiments, outcoupling optical elements 1282, 1284, 1286, 1288, 1290 are diffractive features that form a diffractive pattern or diffractive optical element (also referred to herein as a DOE). Preferably, the DOEs have a sufficiently low diffraction efficiency (ratio of diffracted beam intensity to incident beam intensity) such that only a portion of the light is deflected toward the eye 4 due to each intersection of the DOEs, while the remainder is deflected towards the eye 4 (total internal TIR). It continues to move through the waveguide through reflection. Thus, the light carrying the image information is split into a number of related outgoing beams exiting the waveguide at a number of locations and the result is a fairly uniform direction towards the eye 4 as this particular collimated beam bounces back and forth within the waveguide. is the outgoing emission pattern.

[0091] In some embodiments, one or more DOEs may be switchable between "on" states that actively diffract them and "off" states that do not significantly diffract them. For example, a switchable DOE can include a polymer dispersed liquid crystal layer in which the microdroplets comprise a diffraction pattern in a host medium, and the refractive index of the microdroplets can be switched to substantially match the refractive index of the host medium (in which case the pattern does not significantly diffract incident light) or the microdroplet can be switched to an index that does not match the index of the host medium (in which case the pattern actively diffracts incident light).

[0092] In some embodiments, camera assembly 500 to capture images of eye 4 and/or tissue around eye 4, eg, to detect user inputs and/or to monitor a physiological state of the user. (eg, a digital camera including visible light and infrared cameras) may be provided. As used herein, a camera may be any image capture device. In some embodiments, camera assembly 500 may include an image capture device and a light source for projecting light (eg, infrared) to an eye, which light is then reflected by the eye and directed to the image capture device. can be detected by In some embodiments, camera assembly 500 may be attached to frame 64 ( FIG. 2 ), eg, as discussed herein, camera assembly 500 to make various decisions regarding a user's physiological state. ) may be in electrical communication with processing modules 70 and/or 72 capable of processing image information from . It will be appreciated that information about the user's physiological state can be used to determine the user's behavioral or emotional state. Examples of such information include the user's movements and/or the user's facial expressions. The user's behavioral or emotional state may then be triangulated with the collected environmental and/or virtual content data to determine relationships between behavioral or emotional state, physiological state, and environmental or virtual content data. In some embodiments, one camera assembly 500 may be utilized for each eye to separately monitor each eye.

[0093] Referring now to FIG. 7, an example of outgoing beams output by a waveguide is shown. Although one waveguide is illustrated, it will be appreciated that other waveguides within waveguide assembly 1178 (FIG. 6) may function similarly, where waveguide assembly 1178 includes multiple waveguides. Light 400 is injected into the waveguide 1182 at the input surface 1382 of the waveguide 1182 and propagates within the waveguide 1182 by TIR. At points where light 400 impinges on DOE 1282, a portion of the light exits the waveguide as outgoing beams 402. Outgoing beams 402 are illustrated as being substantially parallel, but as discussed herein, these outgoing beams may also be redirected to propagate into eye 4 at any angle, depending on the depth plane associated with waveguide 1182. (eg, form divergent exit beams). The substantially parallel outgoing beams form a waveguide with outcoupling optical elements that outcouple the light to form images that appear to be set on a depth plane at a great distance from the eye 4 (eg optical infinity). It will be appreciated that it can be indicated. Other waveguides or other sets of outcoupling optical elements may output a more divergent outgoing beam pattern, which will require the eye 4 to adjust to a closer distance to focus on the retina and the optical It will be interpreted by the brain as light from a distance closer to the eye 4 than infinity.

[0094] In some embodiments, a full color image may be formed in each depth plane by overlaying images on component colors, eg, each of three or more component colors. 8 illustrates an example of a stacked waveguide assembly including images where each depth plane is formed using a number of different component colors. Although the illustrated embodiment shows depth planes 14a-14f, more or less depths may also be considered. Each depth plane has three component color images associated with it: a first image of a first color (G); a second image of a second color (R); and a third image of a third color (B). The different depth planes are indicated in the drawing by different numbers for diopters (dpt) followed by the letters G, R and B. By way of example only, the numbers following each of these letters indicate diopters (1/m) or the inverse distance of the depth plane from the viewer, and each box in the figures represents an individual component color image. . In some embodiments, the exact placement of depth planes for different component colors can be varied to account for differences in the eye's focusing of different wavelengths of light. For example, different component color images for a given depth plane can be placed on depth planes corresponding to different distances from the user. Such an arrangement may increase eyesight and user comfort and/or reduce chromatic aberrations.

[0095] In some embodiments, light of each component color may be output by one dedicated waveguide, and consequently, each depth plane may have multiple waveguides associated with it. In these embodiments, each box in the drawings containing the letters G, R or B can be understood to represent a separate waveguide, and three waveguides can be provided per depth plane, where three component color Images are presented per depth plane. Although the waveguides associated with each depth plane are shown adjacent to each other in this figure for ease of illustration, it will be appreciated that in a physical device the waveguides may all be arranged in a stack with one waveguide per level. In some other embodiments, multiple component colors can be output by the same waveguide, eg only a single waveguide can be provided per depth plane.

[0096] With continued reference to FIG. 8, in some embodiments, G is a green color, R is a red color, and B is a blue color. In some other embodiments, other colors associated with other wavelengths of light, including magenta and cyan, may be substituted for, or used in addition to, one or more of red, green, or blue. In some embodiments, features 198, 196, 194 and 192 may be active or passive optical filters configured to selectively block light from the surrounding environment to the viewer's eyes.

[0097] It will be appreciated that throughout this disclosure references to light of a given color will be understood to include light of one or more wavelengths within the range of wavelengths of light perceived by the viewer as being of that given color. For example, red light can include light at one or more wavelengths in the range of about 620-780 nm, green light can include light in one or more wavelengths in the range of about 492-577 nm, and blue light can include light in the range of about 435-493 nm. may include light of one or more wavelengths of

[0098] In some embodiments, light source 2040 (FIG. 6) may be configured to emit light at one or more wavelengths outside the range of visual perception of a viewer, eg, infrared and/or ultraviolet wavelengths. In addition, the incoupling, outcoupling and other light redirecting structures of the waveguides of the display 1000 direct and emit this light out of the display towards the user's eye 4 for, for example, imaging and/or user stimulation applications. can be configured.

[0099] Referring now to FIG. 9A, in some embodiments light impinging on a waveguide may need to be redirected to incoupling it into the waveguide. An incoupling optical element can be used to redirect and incouple the light into its corresponding waveguide. 9A illustrates a cross-sectional side view of an example of a plurality of stacked waveguides or set of stacked waveguides 1200 each including an incoupling optical element. The waveguides may each be configured to output light of one or more different wavelengths, or one or more different ranges of wavelengths. Stack 1200 may correspond to stack 1178 (FIG. 6), wherein the illustrated waveguides of stack 1200 allow light from one or more of image implantation devices 1200, 1202, 1204, 1206, 1208 to It will be appreciated that may correspond to a portion of plurality of waveguides 1182, 1184, 1186, 1188, 1190, except that light is injected into the waveguides from a position requiring light to be redirected for incoupling.

[0100] The illustrated set 1200 of stacked waveguides includes waveguides 1210, 1220, and 1230. Each waveguide includes an associated incoupling optical element (which may also be referred to as a light input area on the waveguide), e.g., incoupling optical element 1212 is a major surface (e.g., upper surface of waveguide 1210). major surface), and incoupling optical element 1224 is disposed on a major surface (eg, upper major surface) of waveguide 1220, incoupling optical element 1232 of waveguide 1230. disposed on a major surface (eg, an upper major surface). In some embodiments, one or more of the incoupling optical elements 1212, 1222, 1232 may be disposed on a lowermost major surface of each waveguide 1210, 1220, 1230 (in particular, one or more incoupling optical elements 1210, 1220, 1230). where the ring optical elements are reflective deflecting optical elements). As illustrated, incoupling optical elements 1212, 1222, 1232 have an upper major surface of their respective waveguides 1210, 1220, 1230, particularly if such incoupling optical elements are transmissive deflecting optical elements. (or on top of the next lower waveguide). In some embodiments, incoupling optical elements 1212 , 1222 , 1232 may be disposed in the body of each waveguide 1210 , 1220 , 1230 . In some embodiments, as discussed herein, incoupling optical elements 1212, 1222, 1232 are wavelength selective, such that they selectively redirect one or more wavelengths of light while transmitting other wavelengths of light. Although illustrated on one side or corner of its respective waveguide 1210 , 1220 , 1230 , incoupling optical elements 1212 , 1222 , 1232 may, in some embodiments, ).

[0101] As illustrated, incoupling optical elements 1212, 1222, 1232 may be laterally offset from each other. In some embodiments, each incoupling optical element can be offset such that it receives the light without passing through another incoupling optical element. For example, each incoupling optical element 1212, 1222, 1232 can be configured to receive light from a different image injection device 1200, 1202, 1204, 1206, and 1208 as shown in FIG. 6; may be separate (eg, spaced laterally) from other incoupling optical elements 1212 , 1222 , 1232 so that it substantially transmits light from other ones of incoupling optical elements 1212 , 1222 , 1232 . do not receive

[0102] Each waveguide also includes associated light distribution elements, e.g., light distribution elements 1214 are disposed on a major surface (eg, a top major surface) of waveguide 1210, and the light distribution elements ( 1224 is disposed on a major surface (eg, top major surface) of waveguide 1220 , and light distribution elements 1234 are disposed on a major surface (eg, top major surface) of waveguide 1230 . In some other embodiments, light distribution elements 1214, 1224, 1234 may be disposed on a lowermost major surface of associated waveguides 1210, 1220, 1230, respectively. In some other embodiments, the light distribution elements 1214, 1224, 1234 may be disposed on both the top and bottom major surfaces of the associated waveguides 1210, 1220, 1230, respectively; Alternatively, the light distribution elements 1214, 1224, 1234 may be disposed on different ones of the top and bottom major surfaces of different associated waveguides 1210, 1220, 1230, respectively.

[0103] The waveguides 1210, 1220, 1230 may be spaced and separated by, for example, gas, liquid and/or solid material layers. For example, as illustrated, layer 1218a can separate waveguides 1210 and 1220; Layer 1218b may separate waveguides 1220 and 1230. In some embodiments, layers 1218a and 1218b are formed of low refractive index materials (ie, materials that have a lower refractive index than the material forming the immediately adjacent one of waveguides 1210 , 1220 , 1230 ). Preferably, the refractive index of the material forming the layers 1218a and 1218b is at least 0.05 less than the refractive index of the material forming the waveguides 1210, 1220 and 1230, or at least 0.10 less. Advantageously, the lower index layers 1218a and 1218b reduce the total internal reflection (TIR) of light through the waveguides 1210, 1220, and 1230 (eg, the TIR between the top and bottom major surfaces of each waveguide). may serve as facilitating cladding layers. In some embodiments, layers 1218a and 1218b are formed of air. Although not illustrated, it will be appreciated that the top and bottom portions of the illustrated set of waveguides 1200 may include immediately adjacent cladding layers.

[0104] Preferably, for ease of manufacture and other considerations, the material forming waveguides 1210, 1220, 1230 is similar or identical, and the material forming layers 1218a, 1218b is similar or identical. do. In some embodiments, the material forming waveguides 1210, 1220, 1230 can be different between one or more waveguides, and/or the material forming layers 1218a, 1218b can still have the various refractive indices noted above. You can be different while maintaining relationships.

[0105] With continued reference to FIG. 9A, light rays 1240, 1242, 1244 are incident on set of waveguides 1200. It will be appreciated that light rays 1240, 1242, 1244 can be injected into waveguides 1210, 1220, 1230 by one or more image injection devices 1200, 1202, 1204, 1206, 1208 (FIG. 6). will be.

[0106] In some embodiments, light rays 1240, 1242, 1244 have different properties, eg, different wavelengths or different ranges of wavelengths, which may correspond to different colors. Incoupling optical elements 1212, 122, 1232, respectively, deflect incident light such that it propagates by TIR through a respective one of waveguides 1210, 1220, 1230.

[0107] For example, incoupling optical element 1212 may be configured to deflect light ray 1240 having a first wavelength or range of wavelengths. Similarly, transmitted light ray 1242 impinges on and is deflected by incoupling optical element 1222 configured to deflect light of a second wavelength or range of wavelengths. Similarly, light ray 1244 is deflected by incoupling optical element 1232 configured to selectively deflect light at a third wavelength or range of wavelengths.

[0108] With continued reference to FIG. 9A, deflected rays 1240, 1242, 1244 are deflected such that they propagate through corresponding waveguides 1210, 1220, 1230; That is, each waveguide's incoupling optical elements 1212, 1222, and 1232 deflect light into its corresponding waveguide to incouple light into its corresponding waveguide 1210, 1220, 1230. Rays 1240, 1242, and 1244 are deflected by TIR to angles that cause light to propagate through respective waveguides 1210, 1220, and 1230. Rays 1240, 1242, 1244 propagate by TIR through each waveguide 1210, 1220, 1230 until impinging on corresponding light distribution elements 1214, 1224, 1234 of the waveguide.

[0109] Referring now to FIG. 9B, a perspective view of the example of the plurality of stacked waveguides of FIG. 9A is illustrated. As mentioned above, incoupled light rays 1240, 1242, 1244 are deflected by incoupling optical elements 1212, 1222, 1232, respectively, and then waveguides 1210, 1220, 1230 are propagated by TIR within Light rays 1240, 1242, and 1244 then impinge on light distribution elements 1214, 1224, and 1234, respectively. Light distribution elements 1214, 1224, 1234 deflect light rays 1240, 1242, 1244 so that they propagate towards outcoupling optical element 1250, 1252, 1254, respectively.

[0110] In some embodiments, the light distribution elements 1214, 1224, 1234 are orthogonal pupil expanders (OPEs). In some embodiments, OPEs deflect or distribute light to outcoupling optical elements 1250, 1252, 1254 and also determine the beam or spot size of the light as it propagates to the outcoupling optical elements. can increase In some embodiments, light distribution elements 1214, 1224, 1234 can be omitted, and incoupling optical elements 1212, 1222, 1232 are outcoupled, eg, when the beam size is already the desired size. It may be configured to deflect light directly to ring optical elements 1250, 1252, 1254. For example, referring to FIG. 9A , light distribution elements 1214 , 1224 , and 1234 may be replaced with outcoupling optical elements 1250 , 1252 , and 1254 , respectively. In some embodiments, the outcoupling optical elements 1250, 1252, 1254 are exit pupils (EPs) or exit pupil expanders (EPEs) that direct light to the viewer's eye 4 (FIG. 7).

[0111] Thus, with reference to FIGS. 9A and 9B, in some embodiments, a set of waveguides 1200 includes waveguides 1210, 1220, 1230; incoupling optical elements 1212 for each component color. , 1222, 1232), light distribution elements (eg, OPEs) 1214, 1224, 1234, and outcoupling optical elements (eg, EPs) 1250, 1252, 1254. Waveguides ( 1210, 1220, 1230 can be stacked with an air gap/cladding layer between each waveguide Incoupling optical elements 1212, 1222, 1232 (different incoupling optical elements can ) redirects or deflects the incident light into its own waveguide, since the light is then propagated at an angle that will result in a TIR within each waveguide 1210, 1220, 1230. In the illustrated example, the ray 1240 ( eg blue light) is deflected by the first incoupling optical element 1212 and then continues to bounce along the waveguide, in the manner previously described, to the light distribution elements (eg OPEs) 1214 ) and then interacts with an outcoupling optical element (eg, EPs) 1250. Rays 1242 and 1244 (eg, green and red light, respectively) will pass through the waveguide 1210, and 1242 impinges on and is deflected by incoupling optical element 1222. Light ray 1242 then bounces along waveguide 1220 through the TIR to its light distribution element (e.g., OPEs). ) 1224 and then to outcoupling optical elements (eg, EPs) 1252. Finally, light ray 1244 (eg, red light) passes through waveguide 1220 to waveguide 1230. ) impinges on the light incoupling optical elements 1232. The light incoupling optical elements 1232 cause the light ray 1244 by TIR to the light distribution element (eg, OPEs) 1234, and then deflects the ray to propagate to outcoupling optical elements (eg, EPs) 1254 by TIR. The outcoupling optical element 1254 then finally outcouples the light ray 1244 to the viewer, which also receives the outcoupled light from the other waveguides 1210 and 1220.

[0112] FIG. 9C illustrates a top-down plan view of the example of the plurality of stacked waveguides of FIGS. 9A and 9B. As illustrated, the waveguides 1210, 1220, 1230 are vertically aligned, with an associated light distribution element 1214, 1224, 1234 and an associated outcoupling optical element 1250, 1252, 1254 of each waveguide. It can be. However, as discussed herein, incoupling optical elements 1212, 1222, 1232 are not vertically aligned; Rather, the incoupling optical elements are preferably non-overlapping (eg spaced laterally as seen in a top-down view). As discussed further herein, this non-overlapping spatial arrangement facilitates the injection of light from different sources into different waveguides on a one-to-one basis, thereby allowing a particular light source to be uniquely coupled to a particular waveguide. In some embodiments, arrangements comprising spatially-separated incoupling optical elements that do not overlap may be referred to as a shifted pupil system, and the incoupling optical elements of such arrangements may correspond to sub-pupils. .

Bragg-reflective structures based on liquid crystals

[0113] In general, liquid crystals have physical properties that may be intermediate to conventional fluids and solids. Although liquid crystals are fluid-like in some aspects, unlike most fluids, the arrangement of molecules within liquid crystals exhibits some structural order. Different types of liquid crystals include thermotropic, lyotropic and polymeric liquid crystals. The thermotropic liquid crystals disclosed herein are implemented in phases including various physical states, for example, a nematic state/phase, a smectic state/phase, a chiral nematic state/phase, or a chiral smectic state/phase. It can be.

[0114] As described herein, the liquid crystals of the nematic state or phase have a long-range directional order (its long axes are approximately parallel), while having relatively little positional order (the rods). -shaped) or discotic (disc-shaped) organic molecules. Thus, organic molecules can flow freely, while still retaining their long-range directional order, with the center of mass positions randomly distributed as in a liquid. In some implementations, liquid crystals in a nematic phase can be uniaxial; That is, the liquid crystals have one axis that is longer and preferred, and the other two are approximately equivalent. In other implementations, liquid crystals can be biaxial; That is, in addition to orienting along its major axis, the liquid crystals may also be oriented along the secondary axis.

[0115] As described herein, liquid crystals of a smectic state or phase may have organic molecules that form relatively well-defined layers that can slide over one another. In some implementations, the liquid crystals of the smectic phase can be positionally ordered along one direction. In some implementations, the long axes of the molecules can be oriented along a direction substantially perpendicular to the plane of the liquid crystal layer, while in other implementations, the long axes of the molecules can be tilted with respect to the direction perpendicular to the plane of the layer.

[0116] Herein and throughout this disclosure, nematic liquid crystals are composed of rod-shaped molecules in which the long axes of neighboring molecules are approximately aligned with each other. To describe this anisotropic structure, a dimensionless unit vector n called a director can be used to describe the direction of preferred orientation of liquid crystal molecules.

[0117] Herein and throughout this disclosure, the inclination angle or oblique angle (Φ) is measured in a plane perpendicular to the major surface (x-y plane) of the liquid crystal layers or of the substrate, eg, the x-z plane, and is measured in the alignment direction and the main surface. It may refer to an angle measured between a surface or a direction parallel to a major surface, such as the x-direction.

[0118] Herein and throughout this disclosure, the azimuthal or rotational angle (φ) is used to describe the angle of rotation about the layer normal direction, or axis normal to the major surface of the liquid crystal layer, which is It is measured in a plane parallel to the major surface of the layers or of the substrate, such as the x-y plane, and between an alignment direction, such as the stretch direction or direction of the director, and a direction parallel to the major surface, such as the y-direction.

[0119] Herein and throughout this disclosure, when referred to as being substantially equal between different zones, angles such as total obliquity angle (Φ) or rotation angle (φ) mean the average alignment angles are, e.g., about 1 %, about 5% or about 10%, although in some cases it will be appreciated that the average alignment can be greater.

[0120] Herein and throughout this specification, a duty cycle is defined as, e.g., between a first lateral dimension of a first zone having liquid crystal molecules aligned in a first alignment direction and a lattice period of a zone having the first zone. can refer to rain. Where applicable, the first zone corresponds to a zone in which the alignment of liquid crystals does not fluctuate between different zones.

[0121] As described herein, liquid crystals in a nematic or smectic state may also exhibit chirality. These liquid crystals are referred to as being able to be in either a chiral phase or a cholesteric phase. In the chiral or cholesteric phase, liquid crystals can exhibit a twisting of molecules perpendicular to the director, with the molecular axis parallel to the director. Finite twist angles between adjacent molecules result from their asymmetric packing, which results in long-range chiral ordering.

[0122] As described herein, liquid crystals of a chiral smectic state or phase can be configured such that the liquid crystal molecules have a positional order in a layered structure, and the molecules are tilted at a finite angle with respect to the layer normal. In addition, chirality can induce successive orientational twists of the liquid crystal molecules in the direction of the layer normal with respect to the direction perpendicular to the layer normal from one liquid crystal molecule to the next, and thus a helical twist of the molecular axis along the layer normal. create a sting

[0123] As described herein and throughout this disclosure, the chiral structure extends in a direction perpendicular to the director, such as the layer depth direction, and continues in a rotational direction, such as clockwise or counterclockwise. refers to a plurality of liquid crystal molecules in the cholesteric phase, which are rotated or twisted into In one aspect, directors of liquid crystal molecules of a chiral structure can be characterized as a helix with a helical pitch.

[0124] As described herein, liquid crystals of the cholesteric phase displaying chirality correspond to a length in the layer depth direction corresponding to a net rotation angle of liquid crystal molecules of chiral structures by one full rotation in the first rotation direction. It can be described as having a chiral pitch or helical pitch (p) That is, the helical pitch refers to the distance at which the liquid crystal molecules experience a full 360° twist. The helical pitch (p) can change, for example, when the temperature is changed or when other molecules are added to the liquid crystal host (achiral liquid host material can form a chiral phase when doped with a chiral material) ), allowing the helical pitch p of a given material to be tuned correspondingly. In some liquid crystal systems, the helical pitch is of the same order as the wavelength of visible light. As described herein, liquid crystals that display chirality also have a twist angle, or rotation angle (Φ), which can refer to the relative azimuthal rotation between successive liquid crystal molecules, e.g. in the layer normal direction, and e.g. , can be described as having a net twist angle or net rotation angle, which can refer to the relative azimuthal rotation between the uppermost and lowermost liquid crystal molecules over a specified length, such as the length of a chiral structure or the thickness of a liquid crystal layer.

[0125] According to various embodiments described herein, liquid crystals having various states or phases as described above exhibit various desirable material properties including, for example, birefringence, optical anisotropy, and manufacturability using thin film processes. can be configured to provide For example, by changing the surface conditions of the liquid crystal layers and/or mixing different liquid crystal materials, grating structures exhibiting spatially varied diffraction properties, such as gradient diffraction efficiencies, can be fabricated.

[0126] As described herein, “polymerizable liquid crystals” may refer to liquid crystal materials that can be polymerized, eg, in-situ photopolymerized, and also may be described herein as reactive mesogens (RMs).

[0127] It will be appreciated that the liquid crystal molecules may be polymerizable in some embodiments and once polymerized may form a large network with other liquid crystal molecules. For example, liquid crystal molecules may be linked by chemical bonds or by linking chemical species with other liquid crystal molecules. When bonded together, the liquid crystal molecules can form liquid crystal domains having substantially the same orientations and positions as before being linked together. For convenience of description, the term “liquid crystal molecule” is used herein to refer to both liquid crystal molecules before polymerization and liquid crystal domains formed by these molecules after polymerization.

[0128] According to certain embodiments described herein, light-polymerizable liquid crystal materials may be configured to form Bragg-reflecting structures, such as diffraction gratings, exhibiting birefringence, chirality, and ease of multi-coating. can be exploited to create diffraction gratings with different material properties, e.g., birefringence, chirality, and thickness, which have different diffraction properties, e.g., diffraction efficiency, wavelength selectivity and may result in off-axis diffraction angular selectivity.

[0129] It will be appreciated that, as described herein, a "transmissive" or "transparent" structure, such as a transparent substrate, may pass at least a portion of incident light, such as at least 20, 30, or 50%. Thus, the transparent substrate may be a glass, sapphire or polymeric substrate in some embodiments. In contrast, a “reflective” structure, such as a reflective substrate, may reflect at least a portion of incident light therefrom, such as at least 20, 30, 50, 70, 90% or more.

[0130] The optical properties of a grating are determined by its physical structures (eg, periodicity, depth, and duty cycle) as well as its material properties (eg, refractive index, absorption, and birefringence). When liquid crystals are used, the optical properties of the grating can be controlled, for example, by controlling the molecular orientation or distribution of the liquid crystal materials. For example, by varying the molecular orientation or distribution of the liquid crystal material across the grating area, the grating can exhibit graded diffraction efficiencies. These approaches are described below with reference to the figures.

Cholesteric Liquid Crystal Diffraction Grating (CLCG)

[0131] As described above with reference to FIGS. 6 and 7, display systems according to various embodiments described herein may include optical elements that may include diffraction gratings, such as incoupling optical elements, outcoupling optical elements and light distribution elements. For example, as described above with reference to FIG. 7 , light 400 injected into the waveguide 1182 at the input surface 1382 of the waveguide 1182 is reflected within the waveguide 1182 by total internal reflection (TIR). It spreads. At points where light 400 impinges on out-coupling optical element 1282, a portion of the light exits the waveguide as outgoing beams 402. In some implementations, any of optical elements 1182, 1282 or 1382 can be configured as a diffraction grating.

[0132] Efficient light in-coupling into (or out-coupling from) the waveguide 1182 enables waveguide-based see-through displays, eg, for virtual/augmented/mixed display applications. This can be a challenge in design. For these and other applications, it is desirable to have a diffraction grating formed of a material whose structure is configurable to optimize various optical properties, including diffractive properties. Preferred diffraction properties include, among other properties, polarization selectivity, spectral selectivity, angular selectivity, high spectral bandwidth and high diffraction efficiency. To address these and other needs, in various embodiments disclosed herein, optical element 1282 is configured as a cholesteric liquid crystal diffraction grating (CLCG). As described below, CLCGs according to various embodiments can be configured to optimize polarization selectivity, bandwidth, phase profile, spatial variation of diffractive properties, spectral selectivity, and high diffraction efficiencies, among other things.

[0133] Hereinafter, various embodiments of CLCGs constructed as a reflective liquid crystal diffraction grating comprising a cholesteric liquid crystal (CLC) optimized for various optical properties are described. Diffraction gratings generally have a periodic structure that splits and diffracts light into several light beams traveling in different directions. The directions of these beams depend, among other things, on the period of the periodic structure and the wavelength of the light. To optimize certain optical properties, e.g., diffraction efficiencies, for certain applications, such as the outcoupling optical element 1282 (FIGS. 6, 7), the various material properties of the CLC are as described below. can be optimized.

[0134] As described above, the liquid crystal molecules of the cholesteric liquid crystal (CLC) layer in the chiral (nematic) phase or the cholesteric phase as a function of the position of the film in the normal direction or depth direction of the liquid crystal layer are the continuation of the director. It is characterized by a plurality of liquid crystal molecules arranged to have symmetrical azimuthal twists. As described herein, liquid crystal molecules arranged with successive azimuthal twists are collectively referred to herein as a chiral structure. As described herein, the angle of azimuthal twist or rotation (Φ) is described as the angle between the directors of the liquid crystal molecules with respect to the direction parallel to the layer normal, as described above. The spatially varying director of liquid crystal molecules of a chiral structure forms a helical pattern in which the helical pitch p is defined as the distance by which the director rotates by 360 degrees (e.g., in the layer normal direction of the liquid crystal layer) as described above. can be described as forming As described herein, a CLC layer configured as a diffraction grating has a lateral dimension in which the molecular structures of the liquid crystals repeat periodically in a lateral direction normal to the depth direction. This periodicity in the lateral direction is referred to as the grating period (Λ).

[0135] According to various embodiments described herein, a diffraction grating includes a cholesteric liquid crystal (CLC) layer including a plurality of chiral structures, each chiral structure extending in a layer depth direction by at least a helical pitch and It includes a plurality of liquid crystal molecules continuously rotated in the first rotation direction. The helical pitch is a length in a layer depth direction corresponding to a net rotation angle of liquid crystal molecules of chiral structures by one full rotation in the first rotation direction. The arrangements of liquid crystal molecules of chiral structures are periodically fluctuated in the lateral direction perpendicular to the layer depth direction.

[0136] FIG. 10 illustrates a cross-sectional side view of a cholesteric liquid crystal (CLC) layer 1004 comprising a plurality of uniform chiral structures. The CLC 1004 includes a CLC layer 1008 comprising liquid crystal molecules arranged as a plurality of chiral structures 1012-1, 1012-2, ... 1012-i, where each chiral structure has a plurality of of liquid crystal molecules, where i is any suitable integer greater than 2. For example, the chiral structure 1012-1 comprises a plurality of liquid crystal molecules 1012-1-1, 1012-1-2, .. 1012-1-j), where j is any suitable integer greater than 2. The liquid crystal molecules of each chiral structure are continuously rotated in the first rotation direction. In the illustrated embodiment, the liquid crystal molecules are continuously rotated clockwise when viewed in the positive z-axis direction (eg, the direction of the axis arrow) or the direction of propagation of the incident light beams 1016-L and 1016-R. For example, in the illustrated embodiment, the liquid crystal molecules 1012-1-1, 1012-1-2, ... 1012-1-j of the chiral structure 1012-1 are, for example, in the positive x-direction. angle of rotation for ) is rotated continuously. In the illustrated embodiment, for illustrative purposes, each of the plurality of liquid crystal molecules of the chiral structures 1012-1, 1012-2, ... 1012-i between opposite ends in the z-direction undergoes one full rotation. Or rotated by a turn, so that the net rotation angle of the liquid crystal molecules is about 360°. Consequently, the chiral structures 1012-1, 1012-2, ..., 1012-i have a length L in the z-direction equal to a helical pitch p. However, without limiting the embodiments to this, chiral structures 1012-1, 1012-2, ... 1012-i can be any number of full rotations greater or less than 1, any number less than or greater than 360°. can have any suitable length L in the z-direction that is shorter or longer than the suitable net rotation angle of , and/or the helical pitch p. For example, in various embodiments described herein, the number of full turns of the chiral structures is 1 to 3, 2 to 4, 3 to 5, 4 to 6, 5 to 7, 6 to 8, 7, among other numbers. to 9, or 8 to 10.

[0137] Still referring to FIG. 10, the continuous rotation angle between adjacent liquid crystal molecules in the z-direction ( ) may be the same according to some embodiments, or may be different according to some other embodiments. As an example, in the illustrated embodiment, the length of the chiral structures 1012-1, 1012-2, ... 1012-i is about p and the net rotation angle is 360°, so that adjacent liquid crystal molecules in the z-direction are rotated by about 360°/(m-1), where m is the number of liquid crystal molecules in the chiral structure. For example, for illustrative purposes, each of the chiral structures 1012-1, 1012-2, ... 1012-i has 13 liquid crystal molecules, so that adjacent liquid crystal molecules in the z-direction are separated from each other by about 30 degrees. rotate about Of course, chiral structures may have any suitable number of liquid crystal molecules, in various embodiments.

[0138] Thus, still referring to FIG. 10, adjacent chiral structures in the lateral direction, eg, the x-direction, have similarly arranged liquid crystal molecules. In the illustrated embodiment, chiral structures 1012-1, 1012-2, ... 1012-i are most closely related to liquid crystal molecules of different chiral structures, e.g., light incident surface 1004S, at approximately the same depth. Adjacent liquid crystal molecules are similarly configured to have the same rotation angle, as well as the successive rotation angles of successive liquid crystal molecules of almost the same depth, as well as the net rotation angle of liquid crystal molecules of each chiral structure.

[0139] Hereinafter, the CLC layer 1004 illustrated in FIG. 10 is further described in operation. As explained, the CLC layer 1004 includes chiral structures 1012-1, 1012-2, ... 1012-i with a uniform arrangement in the lateral direction, eg, the x-direction. In operation, when an incident light having a combination of light beams having leftward circular polarization and light beams having rightward circular polarization is incident on the surface 1004S of the CLC layer 1008, by Bragg-reflection, one circular polarization Light with handiness is reflected by the CLC layer 1004, while light with the opposite polarization handiness is transmitted through the CLC layer 1008 without substantial interference. As explained herein and throughout this disclosure, handyness is defined as viewed in the direction of propagation. According to embodiments, the direction of polarization or the handiness of polarization of the light beams 1016-L and 1016-R is matched so that it is the liquid crystal of the chiral structures 1012-1, 1012-2, ... 1012-i. Incident light is reflected when it has the same rotational direction as the molecules. As illustrated, light beams 1016-L with left-handed circular polarization and light beams 1016-R with right-handed circular polarization are incident on surface 1004S. In the illustrated embodiment, the liquid crystal molecules of the chiral structures 1012-1, 1012-2, ... 1012-i move in the direction in which the incident light beams 1016-L, 1016-R move, i.e. positive x. It rotates continuously from the -direction to the clockwise direction, which is the same direction of rotation as the light beams 1016-R with rightward circular polarization. As a result, light beams 1016-R with right-handed circular polarization are substantially reflected, while light beams 1016-L with left-handed circular polarization are substantially transmitted through CLC layer 1004.

[0140] Without wishing to be bound by any theory, under Bragg-reflection, the wavelength (λ) of the incident light may be proportional to the mean or average index of refraction (n) and the helical pitch (p) of the CLC layer, and in some circumstances It can be expressed as satisfying the following condition:

[One]

[0141] Further, the bandwidth of Bragg-reflected wavelengths (Δλ) may be proportional to the birefringence (Δn) of the CLC layer 1004 (e.g., the difference in refractive index between different polarizations of light) and the helical pitch (p), some In circumstances it can be expressed as satisfying the following condition:

[2]

[0142] In various embodiments described herein, the bandwidth (Δλ) is about 60 nm, about 80 nm, or about 100 nm.

[0143] According to various embodiments, the peak reflected intensity within the visible wavelength range, e.g., from about 390 nm to about 700 nm or within the near-infrared wavelength range, e.g., from about 700 nm to about 2500 nm, is about 60%, about 70%, about 80% or greater than about 90%. Also, according to various embodiments, a full width at half maximum (FWHM) may be less than about 100 nm, less than about 70 nm, less than about 50 nm, or less than about 20 nm.

[0144] Figure 11 illustrates a cross-sectional side view of a CLC grating (1150) with differently arranged chiral structures in the lateral direction, eg, varying twist angles in the lateral direction. Similar to the CLC layer 1004 of FIG. 10 , the diffraction grating 1150 is cholesteric (CLC) comprising liquid crystal molecules arranged as a plurality of chiral structures 1162-1, 1162-2, ... 1162-i. liquid crystal) layer 1158, wherein each chiral structure includes a plurality of liquid crystal molecules. For example, the chiral structure 1162-1 comprises a plurality of liquid crystal molecules 1162-1-1, 1162-1-2, .. 1162-1-j). The liquid crystal molecules of each chiral structure are continuously rotated in a first rotational direction in a manner similar to that described with respect to FIG. 10 . In addition, various other parameters of the chiral structures, including the length L, the number of full turns made by the liquid crystal molecules and the number of liquid crystal molecules per chiral structure are similar to the chiral structures described above with respect to FIG. 10 .

[0145] However, in contrast to the illustrated embodiment of FIG. 10, in the illustrated embodiment of FIG. 11, adjacent chiral structures in the lateral direction, eg, the x-direction, have liquid crystal molecules arranged differently. The chiral structures 1162-1, 1162-2, ..., 1162-i are configured differently in the x-direction so that liquid crystal molecules of different chiral structures at almost the same depth have different rotation angles. For example, in the illustrated embodiment, the liquid crystal molecules 1162-1-1, 1162-2 closest to the incident surfaces 1158S of the chiral structures 1162-1, 1162-2, ... 1162-i -1, ... 1162-i-1) are the angles of rotation (e.g., in the positive x-axis direction relative to the positive x-direction), respectively. ) is rotated continuously. In the illustrated embodiment, liquid crystal molecules 1162-1-1, 1162-2-1, . 1162-i-1) is a rotation angle of about 180°. Also, liquid crystal molecules of different chiral structures (most liquid crystal molecules) disposed at almost the same depth level are rotated by almost the same rotation angle with respect to each surface.

[0146] Still referring to FIG. 11A, successive rotational angles of liquid crystal molecules at the same depth level over a period Λ in the x-direction ( ) may be the same according to some embodiments, or may be different according to some other embodiments. In the illustrated embodiment, during the period Λ, when the net rotation angle is 360° as in the illustrated embodiment, adjacent liquid crystal molecules in the x-direction are rotated by about 360°/(m−1), where m is the number of liquid crystal molecules spanning a period (Λ) in the x-direction. For example, for illustrative purposes, there may be seven liquid crystal molecules spanning a period Λ, such that adjacent liquid crystal molecules on the same vertical level in the x-direction are rotated relative to each other by about 30°. Of course, chiral structures may have any suitable number of liquid crystal molecules, in various embodiments.

[0147] For illustrative purposes, it will be appreciated that the CLC layer 1158 is illustrated as having only one period (Λ). Of course, the embodiments are not limited in this respect, and the CLC layer 1158 may have any suitable number of periods determined by the lateral dimension of the CLCG in the x-direction.

[0148] As illustrated by CLCG 1150, when chiral structures are differently arranged in a lateral direction, e.g., in the x-direction, e.g., when continuously rotated, the continuously rotated chiral structures rotate along the x-direction. leads to shifts in the relative phases of the reflected light. This is the rotation angles in the x-axis direction in one period (Λ) ( ) is illustrated with respect to graph 1170 plotting the phase change φ due to continuously rotated chiral structures by . Without being bound by any theory, the relative phase difference (Δφ) of the reflected light 1018 is where x is the position along the lateral direction and Λ is the period. Bandwidth is can be expressed as

[0149] Referring again to FIGS. 10 and 11 and Equations [1] and [2], according to various embodiments, the Bragg-reflected wavelength can be varied by varying the helical pitch p of the chiral structures. . In various embodiments, without being bound by any theory, the helical pitch (p) is determined by increasing or decreasing the helical twisting power (HTP), which refers to the ability of a chiral compound to induce a rotation or twist angle, as described above. may fluctuate. HTP, in turn, can be varied by varying the amount of chiral compounds relative to the amount of non-chiral compounds. In various embodiments, by chemically and/or mechanically mixing a chiral compound with a non-chiral compound, such as a nematic compound, the Bragg-reflection wavelength and hence the color is determined by the helical pitch and the relative fragility of the chiral compound. It may change based on the inverse relationship between the options. In various embodiments disclosed herein, the ratio of the amount of non-chiral compound to the amount of chiral compound is about 20:1, 10:1, 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5, 1:10 or about 1:20.

[0150] In the description above with respect to FIGS. 10 and 11, incident light beams 1016-L and 1016-R are illustrated as propagating in a direction parallel to the layer normal, eg, the z-direction. However, in various applications, light propagating within the waveguide 1182, eg, propagating by total internal reflection (TIR), is off-axis, as described above, eg, with respect to FIGS. 6 and 7 . At an angle it impinges outcoupling optical elements 1282, 1284, 1286, 1288, 1290, eg diffraction gratings. The diffraction gratings described herein can be configured to maximize bandwidth and diffraction efficiency for such configurations, as described below.

[0151] In the above description with respect to FIGS. 10 and 11, liquid crystal molecules are illustrated as not being foregrounded. However, embodiments are not limited thereto, and the liquid crystal molecules may, according to some embodiments, about +/-60 degrees to about +/-90 degrees with respect to a direction parallel to the major surface of the CLCG, eg, with respect to the x-y plane. or about +/-65 degrees to about +/-85 degrees, such as about +/-75 degrees; about +/-35 degrees to about +/-65 degrees or about +/-40 degrees to about +/-60 degrees, such as about +/-50 degrees; It may have a foreground oblique angle (Φ) of about +/-10 degrees to about +/-40 degrees or about +/-15 degrees to about +/-35 degrees, for example about +/-25 degrees. According to some other embodiments, the foreground blind angle Φ may be between about ±15 degrees, or between about ±10 degrees, or between about ±5 degrees, such as 0 degrees.

CLCGs configured for high-bandwidth reflection at off-axis angles of incidence

[0152] FIG. 12 illustrates a cross-sectional side view of a CLC layer 1158 configured for high-bandwidth reflection at off-axis angles of incidence. As described herein, the off-axis angle of incidence is the angle of incidence θ _inc of the incident beam 1216 relative to the direction of the layer normal (eg, the z-direction in FIG. 12 ), which has a non-zero value, which is the angle of reflection ( θ) of Bragg-generating the reflected beam 1220). In some situations, the angle of reflection can be varied to a limited extent by varying λ/Λ. Without being bound by any theory, in some circumstances off-axis reflection can be described based on the relationship:

[3]

where θ _inc is the angle of incidence with respect to the direction of the layer normal, θ is the angle of reflection with respect to the direction of the layer normal, and n is the reflectance of the medium through which the reflected beam propagates. When the CLC layer 1158 is illuminated with the incident beam 1216 at an off-axis angle, the reflectance spectrum may be shifted towards shorter wavelengths. According to various embodiments disclosed herein, the ratio (λ/Λ) is from 0.5 to 0.8, 0.6 to 0.9, 0.7 to 1.0, 0.8 to 1.1, 0.9 to 1.2, 1.0 to 1.6, 1.1 to 1.5, or 1.2 to 1.4. can have a value.

[0153] Without wishing to be bound by any theory, the off-axis angle at which the CLC layer 1158 is configured to Bragg-reflect with high efficiency may also depend on the helical pitch p of the chiral structures.

[0154] Figures 13A and 13B illustrate side cross-sectional views of CLC layers configured for reflection at off-axis angles of incidence. Referring to FIG. 13A , a first cholesteric liquid crystal (CLC) layer 1358A includes a first plurality of chiral structures having a first helical pitch p ₁ . The first CLC layer 1358A is such that the Bragg-reflection is maximized when the first incident light beam 1316A is directed to the incident surface of the CLC layer 1358A at a first off-axis angle (θ _inc,1 ). It has a first helical pitch p ₁ , which results in a first reflected light beam 1320A of a first reflection angle θ ₁ . As illustrated, the CLC layer 1358A is further configured to have a first range 1324A of off-axis incidence angles over which a relatively high diffraction efficiency can be obtained. The first range 1324A may correspond to a range of off-axis angles of incidence, outside which the intensity of the first reflected light beam 1320A drops by more than 1/e, for example. For example, the first range 1324A is a value of θ _inc,1 ±3°, θ _inc,1 ±5°, θ _inc,1 ±7°, θ _inc,1 ±10° or θ _inc,1 ±20°. can have

[0155] Referring to FIG. 13B, a second CLC layer 1358B different from the first cholesteric liquid crystal (CLC) layer 1358A has a first helical pitch (p ₁ ) of the first CLC layer 1358A of FIG. 13A. It includes a second plurality of chiral structures having a second helical pitch (p ₂ ) different from .

[0156] As illustrated, the second CLC layer 1358B is such that the second incident light beam 1316B is at a second off-axis angle θ _inc , _{2 that is different from the first off-axis angle θ inc1 .} A second reflected light beam 1320B is generated having a second reflection angle, θ ₂ , different from the first reflection angle, θ ₁ , when directed to the incident surface of the CLC layer 1358B. As illustrated, the CLC layer 1358B is further configured to have a second range 1324B of off-axis angles, similar to the first range 1324A described above with respect to FIG. 13A .

[0157] FIG. 13C illustrates a cross-sectional side view of a CLCG 1358 comprising multiple CLC layers with different helical pitches in a stacked configuration, for Bragg-reflection at multiple off-axis angles of incidence and high diffraction bandwidth. do. CLCG 1358 includes CLC layers 1358A and 1358B, respectively, described above with respect to FIGS. 13A and 13B formed one on top of the other, eg, in a stacked configuration and in contact with each other. The various parameters of the plurality of CLC layers 1358A, 1358B with different helical pitches allow the CLCG 1358 to achieve high performance over a wider range of off-axis angles than can be achieved using only one CLC. It may be improved or optimized to be configured for diffraction efficiency and efficient reflection at multiple off-axis angles of incidence. For example, in the illustrated embodiments, p ₁ and p ₂ indicate that the resulting first and second ranges 1324A and 1324B are adjacent wavelength ranges that include the first and second ranges 1324A and 1324B. may be chosen to overlap at least partially to provide high diffraction efficiency across the However, in other embodiments, p ₁ and p ₂ may be selected such that the first and second ranges 1324A and 1324B do not overlap.

[0158] In operation, the first and second CLC layers 1358A, 1358B are formed one above the other, so that the first and second incident light beams at first and second off-axis angles θ _inc1 , θ _inc2 When (1316A, 1316B) is directed to the incident surface of the first CLC layer 1358A, the first incident light beam 1316A is substantially reflected by the first CLC layer 1358A at a first reflection angle θ ₁ . On the other hand, the second incident light beam 1358B is substantially transmitted through the first CLC layer 1358A toward the incident surface of the second CLC layer 1358B, and at a second reflection angle θ ₂ , the second CLC layer 1358B ) to be substantially reflected by Although not shown for clarity, it will be appreciated that the concepts described above may be extended to any suitable number of CLC layers.

[0159] As described herein and throughout, a light beam that is “substantially transmitted” through a layer is at least 20%, 30%, 50%, 70% of the incident light intensity as the light exits the layer. % or 90% may refer to the remaining light. Similarly, a light beam that is “substantially reflected” by a layer may refer to light for which at least 20%, 30%, 50%, 70% or 90% of the incident light intensity remains in the reflected light.

[0160] Referring still to FIG. 13C , in various embodiments, the liquid crystal molecules of the first and second CLC layers 1358A, 1358B may have different helical (HTP) molecules as described above. It may contain different amounts of the same chiral compound to have twisting power. For example, the second CLC layer 1358B may have a higher relative amount of the same chiral compound compared to the first CLC layer 1358A. In some embodiments, the pitch (p) may be inversely proportional to the fraction of chiral compounds with respect to the entire liquid crystal compound including chiral and achiral compounds. However, the embodiments are not limited thereto, and the first and second CLC layers 1358A and 1358B may have different chiral compounds.

[0161] In addition, in various embodiments, the liquid crystal molecules of the first and second CLC layers 1358A and 1358B include the same or different chiral compounds, so that the CLC layers 1358A and 1358B have different ratios (λ/Λ) ₁ and λ/Λ ₂ ), respectively, the CLC layers 1358A, 1358B can be configured to have high diffraction efficiencies at different angles of incidence (θ _inc1 , θ _inc2 ), eg, according to Equation [3].

[0162] Still referring to FIG. 13C, the first and second CLC layers 1358A, 1358B may be fabricated such that one is directly above the other, according to some embodiments. For example, a first CLC layer 1358A can be deposited on an alignment layer that provides alignment conditions for the first CLC layer 1358A, followed by a second CLC layer 1358B being deposited on the first CLC layer 1358B. ) can be deposited on. Under these fabrication conditions, the surface of the first CLC layer 1358A may provide alignment conditions for the second CLC layer 1358B. In some other embodiments, each of the CLC layers 1358A, 1358B may be fabricated using separate alignment layers. For example, the first CLC layer 1358A may be formed on the first alignment layer, the second alignment layer may be formed on the first CLC layer 1358A, and the second CLC layer 1358B may be formed on the second alignment layer. on the alignment layer. According to some embodiments, an isolation layer, such as a thin oxide layer, may be formed on the first CLC layer 1358A prior to forming the second alignment layer and/or the second CLC layer 1358B. In still other embodiments, the two CLC layers 1358A, 1358B may be separately fabricated on different substrates and subsequently stacked. In various embodiments, an interlayer may be formed between the two CLC layers 1358A, 1358B to improve adhesion, for example.

[0163] The concepts described above in relation to CLCGs having a plurality of CLC layers optimized for optimal diffraction efficiency at different off-axis angles can be extended to other alternative embodiments. In particular, in some embodiments, instead of forming multiple layers, a single CLC layer can be configured with different zones optimized for optimal diffraction efficiency at different off-axis angles.

[0164] Figure 14 comprises a single CLC layer 1404 having vertical zones with different helical pitches along the depth direction for Bragg-reflection of a plurality of off-axis incident angles in different vertical zones with high diffraction bandwidth. A side cross-sectional view of CLCG 1400 is illustrated. The CLC layer 1404 is a different layer optimized so that a higher diffraction efficiency can be obtained over a wider range of off-axis angles than can be obtained using only one CLC layer with a uniform pitch in the depth direction. parameters, eg a plurality of vertical zones with different helical pitches. In the illustrated embodiment, a single CLC layer 1404 includes a plurality of vertical zones 1404A, 1404B, 1404C and 1404D, each of which may have different helical pitches p ₁ , p ₂ , p ₃ and p ₄ . include Similar to that described above with respect to FIG. 13C , the helical pitches p ₁ , p ₂ , p ₃ and p ₄ have a plurality of vertical regions 1404A, 1404B, 1404C and 1404D, respectively, at angles of incidence ( θ _incA , θ _incB , θ _incC and θ _incD ) can be selected to be configured for optimal diffraction efficiency at the corresponding angles of reflection θ _A , θ _B , θ _C and θ _D at different vertical depths, respectively. ) of the reflected light beam. Also similar to that described above with respect to FIG. 13C , the CLC layer 1404 is further configured to have respective ranges of off-axis angles at which relatively high diffraction efficiency can be obtained. Of course, four vertical zones are illustrated for clarity, but any suitable number of zones may be included in the CLC layer 1404 . Also, the different variations described above with respect to CLCG 1358 of FIG. 13C having multiple CLC layers may be applicable to CLCG 1400 .

[0165] In the illustrated embodiment of FIG. 14, the values of the helical pitches p ₁ , p ₂ , p ₃ and p ₄ decrease as the depth from the entrance surface 1404S increases, such that the helical pitch decreases. A gradient is created in the depth direction (negative z-direction). When the rate of decrease of helical pitch as a function of layer depth in the z-direction is uniform across the thickness of the CLC layer 1404, a graph 1408 representing a linear relationship between depth and helical pitch can be obtained. However, the embodiments are not limited thereto. For example, the helical pitches p ₁ , p ₂ , p ₃ and p ₄ may increase or decrease at any depth and may change at different rates as a function of layer depth, according to some other embodiments.

[0166] The CLC layer 1404 having a gradient of helical pitch can be prepared by varying, eg, increasing or decreasing the helical twisting power (HTP) of liquid crystal molecules at different depths of the CLC layer. HTP, in turn, can be varied spatially by changing the relative amounts of chiral compounds. In various embodiments, by chemically and/or mechanically mixing a chiral compound with a non-chiral compound, such as a nematic compound, at different vertical depths, the helical pitches of vertical regions 1404A, 1404B, 1404C, and 1404D are , based on the inverse relationship between the relative fraction of the chiral compound and the helical pitch, it can be configured for optimal diffraction efficiency at different angles of incidence (θ _incA , θ _incB , θ _incC and θ _incD ), respectively. For example, a mixture of different chemical components (eg chiral di-acrylate monomers and nematic/non-chiral mono-acrylate monomers) that undergo a polymerization process at different reaction rates under UV irradiation can be used. Additionally or alternatively, the HTP can be varied spatially by changing the irradiation conditions (including exposure intensity and/or exposure time) of the UV irradiation at different depths of the CLC layer. HTP can also be varied spatially by varying the pre/post processing of the UV polymerization processing including heat treatment before, after and/or intervening with UV irradiation. For example, when a UV absorbing dye is added to the mixture, an intensity gradient of UV light can be created at different depths of the CLC layer. For example, due to the UV intensity gradient, polymerization near the surface may proceed at a faster rate than in the lower region of the CLC layer. For example, when the cholesteric components are di-acrylates, the probability of incorporation into the resulting polymer can be much higher than the probability of incorporation of a nematic mono-acrylate into the polymer, such as by a factor of two. . Under some circumstances, the overall polymerization rate is controlled such that the depletion of chiral diacrylate near the surface region of the CLC layer creates a di-acrylate concentration gradient in the depth direction of the CLC layer. This in turn initiates diffusion of the di-acrylate towards the surface region of the CLC layer. The result after complete light-polymerization is that the surface region of the CLC layer contains more chiral material and thus has a shorter helical pitch compared to the lower region of the CLC layer, which contains a relatively higher amount of non-chiral compounds. can Under some other circumstances, heat treatment may be added before/after or in between UV irradiation in the polymerization process to control the helical pitch gradient. Accordingly, a helical pitch gradient along the depth direction of the CLC layer can be obtained by controlling the ratio between the two different liquid crystal monomers and/or the amount of UV irradiation, regardless of whether heat treatment is applied or not.

[0167] For some applications, certain optical properties of the diffraction grating, such as off-axis diffraction efficiency, refractive index, wavelength selectivity, polarization, among other parameters, to vary along a lateral direction orthogonal to the layer normal direction. It may be desirable to have selectivity, and phase selectivity. For example, as illustrated above with respect to FIGS. 6 and 7 , for example when a grating is stacked with a waveguide, lateral fluctuations may be desirable such that light propagates laterally. However, under this configuration, the intensity of the light may be attenuated as the light propagates within the waveguide (eg, 1182 in FIG. 7 ). Such configurations may also intentionally skew light intensity across a grating (eg, 1282 in FIG. 7 ) to adapt to spatial and/or angular changes in sensing efficiency associated with the human eye, eg, to maximize user experience. that may be desirable. Accordingly, a need exists for optical elements, such as diffraction gratings, that have spatially varied optical properties.

[0168] FIG. 15 illustrates a cross-sectional side view of a CLCG comprising a CLC layer having lateral zones with different helical pitches along the lateral direction for spatially varied Bragg-reflection. The CLC layer 1424 has a plurality of sides with different liquid crystal material parameters, e.g., helical pitches, so that laterally varying properties, e.g., off-axis incidence angles that vary laterally for Bragg-reflection, can be obtained. It has direction zones. In the illustrated embodiment, the CLC layer 1424 includes a plurality of lateral zones 1424A, 1424B, and 1424c each having a period Λ and having respective helical pitches p ₁ , p ₂ and p ₃ . ). The helical pitches p ₁ , p ₂ and p ₃ are such that the plurality of vertical zones 1424A, 1424B and 1404C have optimal diffraction efficiency at different off-axis angles of incidence θ _incA , θ _incB and θ _incC respectively. , which results in reflected light beams at corresponding reflection angles θ _A , θ _B and θ _C , respectively. Also similar to that described above with respect to FIG. 13C , the different lateral regions of the CLC layer 1424 are further configured to have similar respective ranges of off-axis angles at which relatively high diffraction efficiencies can be obtained. Of course, three vertical zones are illustrated for clarity, but any suitable number of zones may be included in the CLC layer 1424 .

[0169] In the illustrated embodiment of FIG. 15, the magnitudes of the helical pitches p ₁ , p ₂ and p ₃ may vary monotonically in the lateral direction such that a gradient of the helical pitch is created. When the rate of change of the helical pitch in the x-direction is uniform across the width or length of the CLC layer 1424, a linear relationship between the length or width and the helical pitch can be obtained, as illustrated in graph 1428. . However, the embodiments are not limited thereto. For example, the helical pitches p ₁ , p ₂ and p ₃ can increase or decrease in any lateral position and change at different rates in the x-direction along the length or width, according to various other embodiments. there is.

[0170] According to various embodiments, CLC layers can be fabricated to have diffractive properties that are laterally varied by, for example, spatially varied alignment properties of liquid crystal molecules or other material properties. For example, in a manner similar to that described above with respect to FIG. 14 , eg by controlling the UV dosage and/or the ratio between two different liquid crystal monomers in different lateral zones, the lateral helical pitch gradient can change the lateral dimension. can be achieved according to

Waveguides coupled to CLCG for wavelength-selective optical coupling

[0171] As described above, for a variety of applications involving incoupling and outcoupling of light, a waveguide device may be configured to propagate light by total internal reflection (TIR). 16 illustrates an example of an optical light guide device 1600 that includes a waveguide 1604 coupled to a CLCG 1150. The CLCG 1150 includes liquid crystal molecules arranged as a plurality of chiral structures in a manner similar to the chiral structures 1162-1, 1162-2, ... 1162-i described above with respect to FIG. Waveguide 1604 is disposed over CLCG 1150 and is optically coupled to CLCG 1150 . When the elliptically/circularly polarized incident light 1016-R/L has a polarization handiness that matches the rotational direction of liquid crystal molecules of chiral structures, the incident light 1016-R/L is Bragg- The reflected and coupled light is coupled into the waveguide 1604 at an angle that causes the coupled light to travel laterally (eg, in the x-direction) by total internal reflection (TIR). Without being bound by any theory, the TIR condition can be satisfied when the diffraction angle θ is greater than the waveguide's critical angle θ _C . Under some circumstances, the TIR condition can be expressed as

[4]

where n _t is the refractive index of the waveguide 1604. According to various embodiments, n _t may be from about 1 to about 2, from about 1.4 to about 1.8, or from about 1.5 to about 1.7. For example, the waveguide may include a polymer such as polycarbonate or glass.

[0172] FIG. 17A shows a first waveguide coupled to a first CLCG (1750A) and configured to propagate light having a third wavelength (λ ₃ ) by total internal reflection (TIR) when θ>θ _c3 ( 1704A) is illustrated as a first optical light waveguide device 1700A. The first CLCG 1750A has a first period (Λ ₁ ) and a first helical pitch (p ₁ ). According to some embodiments, the first light guiding device 1700A may be configured to propagate light in the visible spectrum (eg, having wavelengths between about 400 nm and 700 nm) by TIR. According to some other embodiments, the first light guiding device 1700A can be configured to propagate light in the infrared spectrum (eg, the near-infrared portion of the spectrum having wavelengths between about 700 nm and 1400 nm) by TIR. As described above with respect to FIGS. 10 and 11 , the Bragg-reflection occurs at the wavelength represented by Equation [1] above and within a bandwidth of wavelengths Δλ represented by Equation [2] above. do. For example, the first CLCG 1750A has a third wavelength (λ ₃ ) in one of blue color (eg, about 450 nm), green color (eg, about 550 nm), red color (eg, about 650 nm), or infrared light. 3 incident light 1736 can be designed to couple by TIR. As illustrated, when Δλ is about 60 nm, about 80 nm, or about 100 nm, first and second lights 1716 and 1726 having first and second wavelengths λ ₁ , λ ₂ , as described above. ) is substantially transmitted because equation [1] is not satisfied for these colors, which is not coupled into the first waveguide 1704 because equation [4] is not satisfied.

[0173] FIG. 17B illustrates a second optical lightguide device 1700B coupled with the first optical lightguide device 1700A illustrated above with respect to FIG. 17A. The optical light waveguide device 1700B is disposed in an optical path following the optical light waveguide device 1700A, is coupled to the second CLCG 1750B, and is coupled to the second CLCG 1750B by total internal reflection (TIR) when θ>θ _c2 . and a second waveguide 1704B configured to propagate a second light 1726 having a wavelength λ ₂ . The second CLCG 1750B has a second period (Λ ₂ ) and a second helical pitch (p ₂ ). As described above with respect to FIG. 17A , first and second lights 1716 and 1726 having first and second wavelengths λ ₁ , λ ₂ may substantially form a first optical light guiding device 1700A. permeates through Among the transmitted first and second lights 1716 and 1726, when the second CLCG 1750B is θ>θ _c2 , blue color (eg, about 450 nm), green color (eg, about 550 nm), and red color ( For example, it may be designed to couple by TIR a second incident light 1726 having a second wavelength (λ ₂ ) in transmitted one of about 650 nm) or infrared. Thus, as illustrated, when Δλ is about 60 nm, about 80 nm, or about 100 nm, as described above, the first light 1716 having the first wavelength λ ₁ is additionally a second light waveguide device ( 1700B) is substantially permeated through.

[0174] FIG. 17C illustrates a third optical lightguide device 1700C coupled with the first and second optical lightguide devices 1700A and 1700B illustrated above with respect to FIG. 17B. The third optical light waveguide device 1700C is disposed in an optical path following the first and second optical light waveguide devices 1700A and 1700B, is coupled to the third CLCG 1750C, and when θ>θ _c1 and a third waveguide 1704C configured to propagate first light 1716 having a first wavelength λ ₂ by total internal reflection (TIR). The third CLCG 1750C has a third period (Λ ₃ ) and a third helical pitch (p ₃ ). As described above with respect to FIG. 17B , first light 1716 having a first wavelength λ ₁ is substantially transmitted through first and second lightguide devices 1700A and 1700B. When θ>θ _c1 , the third CLCG 1750C transmits a first wavelength at one of blue color (eg, about 450 nm), green color (eg, about 550 nm), red color (eg, about 650 nm), or infrared light. It can be designed to couple the first incident light 1716 with (λ ₁ ) by TIR. Thus, as illustrated, when Δλ is about 60 nm, about 80 nm, or about 100 nm, as described above, the first light 1716 having the first wavelength λ ₁ satisfies Equation [4]. Substantially coupled into the third waveguide 1704C.

[0175] Thus, by placing one or more of the first, second and third optical lightguide devices 1700A, 1700B and 1700C in the same optical path, as described above with respect to FIGS. 17A-17C, One or more of the first, second, and third lights 1716, 1726, and 1736 having different wavelengths λ ₁ , λ ₂ , and λ ₃ are transmitted by TIR to the first, second, and third waveguides, respectively. may be coupled to propagate in one of s 1704A, 1704B and 1704C. 17A to 17C , each of the first to third optical light waveguide devices 1704A, 1704B and 1704C includes dedicated first to third waveguides 1704A, 1704B and 1704C and dedicated first to third waveguide devices 1704A, 1704B and 1704C, respectively. 3 CLCGs 1750A, 1750B and 1750C, but embodiments are not limited thereto. For example, a single waveguide can couple Bragg-reflected light from a stack of multiple CLCGs by TIR, as illustrated below with respect to FIG. 18 . In addition, any suitable number of optical light waveguide devices greater than three (or less than three) may also be combined for further selective coupling by Bragg-reflection.

[0176] FIG. 18 illustrates an optical lightguide device 1800 that includes a common waveguide 1704 coupled to a plurality of CLCGs 1750. The plurality of CLCGs 1750 include first to third CLCGs 1750A to 1750C, and by total internal reflection (TIR), the third, second, and first wavelengths λ ₃ , λ ₂ and λ ₁ ) is configured as a stack configured to propagate third, second and first lights 1736, 1726 and 1716, respectively. The TIR is determined by the condition ( and ) occurs when each is satisfied. Also, in a similar manner, the first, second, and third CLCGs 1750A, 1750B, and 1750C, and and selectively Bragg-reflect the third, second, and first lights 1736, 1726, and 1716, respectively. Of course, any suitable number of CLCGs greater than or less than three (or less than three) may be stacked for further selective coupling by Bragg-reflection. Therefore, compared to the embodiments described above with respect to Figs. 17B and 17C, a more compact optical waveguide device 1800 can be obtained by using the common waveguide 1704. Also, instead of three separate CLCG layers (as shown in FIG. 18), the stack of CLCG layers can be arranged as single (or multiple) layers with a helical pitch gradient covering the range of p ₁ to p ₃ . there is.

[0177] As described above with respect to FIGS. 17A to 18, the first to third CLCGs 1750, 1750B, and 1750C are respectively the first to third periods Λ ₁ , Λ _{2 ,} and Λ ₃ . and first to third helical pitches p ₁ , p ₂ and p ₃ , respectively. In various embodiments, each of the CLCGs may be configured such that the wavelength/period ratio (λ/Λ) is between about 0.3 and 2.3, between about 0.8 and 1.8, or between about 1.1 and about 1.5, such as about 1.3. Alternatively, the period Λ is such that the CLCGs are about 1 nm to 250 nm smaller, about 50 nm to 200 nm smaller, or about 80 nm to 170 nm smaller than the respective wavelength λ at which the CLCGs are configured for Bragg-reflection. can be configured. For example, when λ ₁ , λ ₂ and λ ₃ are each within the visible range, such as about 620 nm to about 780 nm, such as about 650 nm (red), about 492 nm to about 577 nm, such as 550 (green), and about 435 nm to about 493 nm, eg, about 450 nm (blue), the corresponding periods λ ₁ , λ ₂ , and λ ₃ are, respectively, from about 450 nm to about 550 nm, such as about 500 nm, from about 373 nm to about 473 nm, such as about 423 nm and about 296 nm to about 396 nm, such as about 346 nm. Alternatively, when λ ₁ , λ ₂ and λ ₃ are in the infrared range, eg, in the near-infrared range of about 750 nm to about 1400 nm, eg, about 850 nm, the corresponding periods Λ ₁ , Λ ₂ and Λ ₃ are about 975 nm to about 1820 nm, such as about 1105 nm. Further, in various embodiments, each of the CLCGs can be configured such that the wavelength/helical pitch ratio (λ/p) is between about 0.6 and 2.6, between about 1.1 and 2.1, or between about 1.4 and about 1.8, such as about 1.6. Alternatively, the helical pitch p is about 50 nm to 350 nm smaller, about 100 nm to 300 nm smaller, or about 140 nm to 280 nm smaller than each wavelength λ at which the CLCGs are configured for Bragg-reflection. It can be configured so that For example, λ ₁ , λ ₂ and λ ₃ are each of about 620 nm to about 780 nm, such as about 650 nm (red), about 492 nm to about 577 nm, such as 550 (green), and about 435 nm to about 493 nm, such as about 450 nm ( blue), the corresponding helical pitches p ₁ , p ₂ and p ₃ are, respectively, from about 350 nm to about 450 nm, such as from about 400 nm, from about 290 nm to about 390 nm, such as from about 340 nm and from about 230 nm to about 330 nm, such as It may be about 280 nm. Alternatively, when λ ₁ , λ ₂ and λ ₃ are in the infrared range, eg, in the near-infrared range of about 750 nm to about 1400 nm, eg, about 850 nm, the corresponding periods Λ ₁ , Λ ₂ and Λ ₃ are about 1200 nm to about 2240 nm, such as about 1360 nm.

Waveguides coupled to CLCG and mirror for wavelength-selective optical coupling

[0178] FIG. 19 illustrates an optical light guide device 1900 that includes a waveguide 1604 coupled to a CLCG 1150, similar to the optical light guide device described above with respect to FIG. 16. As described above with respect to FIGS. 10 and 11 , in operation, when the handiness of polarization of incident light with elliptical/circular polarization has the same rotation direction as the liquid crystal molecules of the chiral structures of CLCG 1150, CLCG ( 1150) substantially reflects incident light. As illustrated, light beams 1016-L with left-handed circular polarization and light beams 1016-R with right-handed circular polarization are incident on surface 1050S. In the illustrated embodiment, the liquid crystal molecules of the chiral structures are continuously rotated clockwise when viewed in the direction in which the incident light beams 1016-L and 1016-R move, that is, the negative z-direction, thereby causing rotation of the liquid crystal molecules. Let the direction match the handiness of light beams 1016-R having right circular polarization. As a result, light beams 1016-R with right-handed circular polarization are substantially reflected by CLCG 1150, while light beam 1016-L with left-handed circular polarization are substantially transmitted through CLCG 1150. do.

[0179] For some applications, it may be desirable to flip the polarization handiness of elliptically or circularly polarized light prior to coupling into an optical waveguide device similar to that described above with respect to FIG. 19. For example, when the polarization handiness of the incident elliptically or circularly polarized light does not match the direction of rotation of the CLCG's chiral structures, so the CLCG is not configured to be Bragg-reflected for coupling into a waveguide as discussed above. may be the case. For some other applications, it may be desirable to recycle the light transmitted through the CLCG due to the lack of matching between the polarization handiness of the incident elliptically or circularly polarized light and the direction of rotation of the chiral structures of the CLCG. To address these and other needs, various embodiments of optical waveguide devices using a polarization converting reflector are disclosed below to address these needs.

[0180] FIG. 20 illustrates an optical light waveguide device 2000 comprising a polarization converting reflector 2004 and a waveguide 1150 coupled to a CLCG 1604, where the CLCG 1604 is configured to receive incident light. and the waveguide 1150 is configured to propagate Bragg-reflected light from the CLCG by total internal reflection (TIR). The polarization converting reflector 2004 is configured such that, upon reflection therefrom, the polarization handiness of the incident elliptically or circularly polarized light is flipped (e.g., left-right or right-left) to the opposite polarization handiness. Instead of the optical waveguide device 2000 being configured to first receive an incident light beam through the waveguide 1150, the optical waveguide device 2000 passes through the CLCG 1604, e.g., the incident light beam 2016 having a leftward circular polarization. -L) is similar to the optical waveguide device 1900 described above with respect to FIG. 19 , except that it is configured to receive first. The incident light beam 2016-L has a polarization handiness that does not match the direction of rotation of the chiral structures of the CLCG 1604 when viewed in the propagation direction (negative z-direction) of the incident light beam 2016-L, so that it No Bragg-reflection by CLCG 1604. As a result, incident light beam 2016-L is substantially transmitted through CLCG 1604 and subsequently reflected by polarization converting reflector 2004. For example, the reflected light beam 2016-R having a right-handed circular polarization thus becomes an incident light beam on the surface 1150S of the waveguide 1150. Due to the flipped polarization handiness, the reflected light beam 2016-R now incident on the surface 1150S of the waveguide 1150 has a direction of propagation of the reflected light beam 2016-R (positive z- direction), it is Bragg-reflected by CLCG 1604, having a handiness of polarization that matches the rotational direction of the chiral structures of CLCG 1604. Reflected light beam 2016-R, which is reflected as an additional reflected beam 2018 reflected at an angle (θ>θ _c ) relative to the layer normal direction (z-axis), is coupled to waveguide 1150 and travels through the waveguide 1150 in a direction (eg, x-direction).

[0181] FIG. 21A illustrates the optical light waveguide device 2000 described above with respect to FIG. 20 under the condition that the incident light beam 2116 is either linearly polarized or unpolarized, each of which has leftward and rightward circular polarization components. can be treated as including both. Under these conditions, the incident light beam 2116 can be coupled into the waveguide by the TIR in opposite lateral directions. For example, an incident light beam having polarization handedness, e.g., left-handedness, that does not match the direction of rotation of the chiral structures of CLCG 1604, similar to that described above with respect to FIG. 20 ( 2116) is substantially transmitted through the CLCG 1604 and subsequently reflected by the polarization converting reflector 2004 so that the polarization handedness is flipped, e.g., to right-handedness. Flipped, coupled into waveguide 1150 and travels through waveguide 1150 in a first lateral direction (eg, positive x-direction). On the one hand, similar to that described above with respect to FIG. 19 , a component of incident light beam 2116 that has a polarization handiness, e.g., right-handness, that matches the direction of rotation of the chiral structures of CLCG 1604, Reflected substantially directly by CLCG 1604, subsequently coupled into waveguide 1150, and through waveguide 1150 in a second lateral direction (eg, negative x-direction) opposite to the first lateral direction. move through

21B shows incident light polarized into two orthogonal elliptically or circularly polarized light beams, e.g., light beams 1016-L with left-handed circular polarization and light beams 1016-R with right-handed circular polarization. Illustrates the optical light waveguide device 2000 described above with respect to FIG. 21A under conditions. Under such conditions, incident light beams 1016-L and 1016-R can be coupled into the waveguide by TIR to propagate in opposite lateral directions, in a manner similar to that described with respect to FIG. 21A above. Components of light beams 1016-L that have a polarization handiness, e.g., left-handness, that do not match the rotational direction of the chiral structures of CLCG 1604, e.g., are substantially transmitted through CLCG 1604 and , subsequently reflected by the polarization converting reflector 2004, the polarization handyness is flipped into a flip, e.g., right-handedness, coupled into the waveguide 1150 and reflected in a first lateral direction (e.g., positive x-direction) through the waveguide 1150. On the one hand, components of incident light beams 1016-R that have a polarization handiness that matches the rotational direction of the chiral structures of CLCG 1604, e.g., right-handness, are substantially directly reflected by CLCG 1604. and is subsequently coupled into the waveguide 1150 and travels through the waveguide 1150 in a second lateral direction (eg, the negative x-direction) opposite to the first lateral direction.

[0183] FIG. 22A includes a first CLCG 2204 having chiral structures having a first rotation direction and a second CLCG 2208 having chiral structures having a second rotation direction opposite to the first rotation direction. Illustrates an optical light guide device 2200 that includes a common waveguide 2204 coupled to a plurality of CLCGs, eg, arranged as a stack. As described above in connection with various embodiments, in operation, when the direction of the polarization direction of the incident light beam matches the direction of rotation of the liquid crystal molecules of the chiral structures of the CLCG, the incident light is reflected. The illustrated optical light waveguide device 2200 is under conditions where the incident light beam 2116 is either linearly polarized or unpolarized. Under these conditions, the incident light beam 2116 can be coupled into the waveguide by the TIR in both opposite lateral directions (positive and negative x directions). In the illustrated embodiment, when viewed from the direction in which the incident light 2116 travels, i.e., the negative z-direction, the liquid crystal molecules of the chiral structures of the first CLCG 2204 are continuously rotated clockwise, while the second CLCG 2116 rotates continuously in the clockwise direction. The liquid crystal molecules of the chiral structures of (2204) are continuously rotated in the opposite counterclockwise direction.

[0184] Referring still to FIG. 22A, a component of an elliptical or circular incident light beam 2116 having a first polarization handiness that matches the direction of rotation of the chiral structures of the first CLCG 2204, e.g., clockwise. The rightwardly polarized component is substantially reflected by the first CLCG 2204, thereby generating a first reflected beam 2118A at an angle θ>θ _c1 with respect to the layer normal direction (z-axis); coupled to common waveguide 2204 and travels through common waveguide 2204 in a first lateral direction (eg, positive x-direction).

[0185] Still referring to FIG. 22A, on the one hand, a component of an elliptical or circular incident light beam 2116 having a second polarization handiness that does not match the direction of rotation of the chiral structures of the first CLCG 2204, e.g. Polarized components are substantially transmitted through the first CLCG 2204 . After being transmitted through the first CLCG 2204, an elliptical or circular incident light beam having a second polarization handyness 2116 that does not match the direction of rotation of the chiral structures of the second CLCG 2208, e.g., counterclockwise. 2116 is substantially reflected by the second CLCG 2208, thereby generating a second reflected beam 2118B of an angle θ>θ _c2 with respect to the layer normal direction (z-axis), and a common coupled to waveguide 2204 and travels through common waveguide 2204 in a second lateral direction (eg, negative x-direction).

[0186] Figure 22B shows, for example, two orthogonal elliptically or circularly polarized light beams of incident light, eg, light beams 1016-L having a left-handed elliptical/circular polarization and light beams having, for example, a right-handed elliptical/circular polarization. Illustrates the optical lightguide device 2000 described above with respect to FIG. 22A under different conditions of polarization with (1016-R). Under these conditions, incident light beams 1016-L and 1016-R have first and second polarization handyness, e.g., left-handedness and right-handedness, incident light beams 1016-L and 1016 -R) into the common waveguide 2204 by the TIR in opposite lateral directions, in a manner similar to that described with respect to FIG. 22A above.

[0187] The embodiments described above with respect to FIGS. 21B and 22B may be particularly advantageous in certain applications, for example, where different light signals (ie images) are encoded with orthogonal circular polarizations. Under these circumstances, light can be coupled in opposite directions (eg, positive and negative x-directions) depending on polarization handiness.

[0188] FIG. 22C includes a first CLCG 2204 having chiral structures having a first rotation direction and a second CLCG 2208 having chiral structures having a second rotation direction opposite to the first rotation direction. Illustrates an optical light guide device 2220 that includes a common waveguide 2250 coupled to a plurality of CLCGs, eg, arranged as a stack. Unlike the embodiments described with respect to FIGS. 22A and 22B , in the optical waveguide device 2220 , a common waveguide 2250 is interposed between the first and second CLCG layers 2204 and 2208 . For illustrative purposes, the illustrated optical light waveguide device 2220 is under the condition that the incident light beam 2116 is either linearly polarized or unpolarized. Under these conditions, the incident light beam 2116 can be coupled into the waveguide by the TIR in opposite lateral directions. In the illustrated embodiment, when viewed from the direction in which the incident light 2116 travels, i.e., the negative z-direction, the liquid crystal molecules of the chiral structures of the first CLCG 2204 are continuously rotated clockwise, while the second CLCG 2116 rotates continuously in the clockwise direction. The liquid crystal molecules of the chiral structures of (2204) are continuously rotated in the opposite counterclockwise direction. Of course, the opposite arrangement is possible.

[0189] Referring still to FIG. 22C, a component of an elliptical or circular incident light beam 2116 having a first polarization handiness that matches the direction of rotation of the chiral structures of the first CLCG 2204, e.g., clockwise. The rightwardly polarized component is substantially reflected by the first CLCG 2204, thereby generating a first reflected beam 2118A at an angle θ>θ _c1 with respect to the layer normal direction (z-axis); This in turn is coupled to the common waveguide 2250 and moves from the outer surface of the first CLCG 2204 before traveling through the common waveguide 2250 in a first lateral direction (eg, negative x-direction) by TIR. It is reflected.

[0190] Still referring to FIG. 22C, on the one hand, an elliptical or circular incident light beam 2116 having a second polarization handiness that does not match the direction of rotation of the chiral structures of the first CLCG 2204, e.g., clockwise. A component of , e.g. a rightwardly polarized component, is substantially transmitted through the first CLCG 2204 and further through the common waveguide 2204, and then substantially reflected by the second CLCG 2208, and thus the layer normal Generates a second reflected beam 2218B at an angle (θ>θ _c2 ) with respect to the direction (z-axis), coupled to common waveguide 2250 and transmitted by TIR in a second lateral direction (e.g., positive x-axis). -direction) through the common waveguide 2250.

Cholesteric liquid crystal off-axis mirror

[0191] As described above in connection with various embodiments, the CLC layer is capable of Bragg- It can be configured as a reflector. Also, one or more CLC layers with different helical pitches can be configured as a wavelength selective Bragg-reflector with high bandwidth. Based on concepts described herein in connection with various embodiments, CLC layers selectively reflect a first wavelength range, eg, infrared wavelengths (eg, near infrared) while transmitting another wavelength range, eg, visible wavelengths. It can be configured as an off-axis mirror configured to Application of various embodiments of CLC off-axis mirrors implemented in eye-tracking systems is now disclosed.

23 is an example of an eye-tracking system 2300 using a cholesteric liquid crystal reflector (CLCR), such as a wavelength-selective CLCR 1150 configured to image a viewer's eye 302, according to various embodiments. exemplify Eye tracking can be used in wearable displays for virtual/augmented/mixed reality display applications, among other applications, including wearable display system 200 of FIG. 2 or systems 700 described in FIGS. 24A-24H . It can be a key feature in interactive vision or control systems. To achieve good eye tracking, it may be desirable to acquire images of the eye 302 at low perspective angles, for which it is in turn desirable to place the eye tracking camera 702b near the central position of the viewer's eyes. can do. However, this position of the camera 702b may obstruct the user's view. Alternatively, the eye-tracking camera 702b may be placed in a lower position or side. However, this position of the camera can increase the difficulty of obtaining robust and accurate eye tracking because eye images are captured at steeper angles. 4, a CLCR (e.g., having a wavelength of 850 nm) to selectively reflect infrared (IR) light 2308 (e.g., having a wavelength of 850 nm) from the eye 302 while transmitting visible light 2304 from the world. 1150), the camera 702b can be positioned away from the user's face while capturing eye images at normal or low perspective angles. This configuration does not obstruct the user's view because visible light is not reflected. The same CLCR 1150 can also be configured as an IR illumination source 2320 as illustrated. The IR illuminator's low perspective angle can lead to more occlusions, eg from the eyebrows, and this configuration allows more reliable detection of specular reflections (which can be a key feature in modern eye-tracking systems).

[0193] With continued reference to FIG. 23, according to various embodiments, the CLCR 1150 includes one or more cholesteric liquid crystal (CLC) layers, each containing a plurality of chiral structures, each as described above, The chiral structure of includes a plurality of liquid crystal molecules extending in the layer depth direction (eg, z-direction) and continuously rotated in the first rotation direction. The arrangements of liquid crystal molecules of chiral structures are periodically fluctuated in a lateral direction perpendicular to the layer depth direction, so that one or more CLC layers substantially transmit second incident light having a second wavelength (λ ₂ ) while substantially transmitting a second incident light having a first wavelength (λ 2 ). ₁ ) to substantially Bragg-reflect the first incident light. As described elsewhere herein, each of the one or more CLC layers transmits, as viewed in the layer depth direction, first and second elliptically or circularly polarized incident light having a handyness of polarization matched to the first rotational direction. configured to substantially transmit, as viewed in the layer depth direction, first and second incident light that is elliptically or circularly polarized having a handyness of polarization opposite to the first direction of rotation, while being configured to substantially Bragg-reflect. . According to embodiments, arrangements of liquid crystal molecules that periodically fluctuate in the lateral direction are arranged to have a period in the lateral direction such that a ratio between the first wavelength and the period is about 0.5 to about 2.0. According to embodiments, the first wavelength is in the near infrared range of about 600 nm to about 1.4 μm, eg about 850 nm, and the second wavelength is in the visible range having one or more colors as described elsewhere herein. According to embodiments, liquid crystal molecules of chiral structures are not foregrounded with respect to a direction normal to the layer depth direction. As configured, the one or more CLC layers are such that the first incident light angle exceeds about 50°, about 60°, about 70° or about 80° with respect to the layer depth direction, e.g., based on Equation [3] described above. It is configured to reflect at an angle θ _R to the layer depth direction (z-direction).

[0194] Referring again to FIG. 2, the eyes of the wearer of a head mounted display (HMD) (e.g., the wearable display system 200 of FIG. 2) may be, for example, a reflective off-axis DOE, which may be a Holographic Optical Element (HOE). (Diffractive Optical Element). The resulting images can be used to track the eye or eyes, image the retina, reconstruct the eye formation in three dimensions, extract biometric information from the eye (eg, iris identification), and the like.

[0195] There are various reasons why a head mounted display (HMD) may use information about the state of the wearer's eyes. For example, this information can be used to estimate the wearer's gaze direction or for biometric identification. However, this problem is challenging due to the short distance between the HMD and the wearer's eyes. Gaze tracking requires a wider field of view, whereas biometric identification is further complicated by the fact that it requires a relatively large number of pixels on the target relative to the iris. For an imaging system that attempts to achieve both of these objectives, the requirements of the two tasks are far apart. Finally, both problems are further complicated by the masking by the eyelids and eyelashes. Embodiments of the imaging systems described herein address some or all of these problems. Various embodiments of the imaging systems 700 described herein with reference to FIGS. 24A-24F may include an HMD (e.g., the wearable display system 200 shown in FIG. 2 and/or It can be used with the display system 1000 shown in FIG. 6).

[0196] FIG. 24A is used for viewing eye 304 and mounted near the wearer's temple (e.g., on frame 64 of wearable display system 200 of FIG. 2, e.g., on the ear stem). Schematically illustrates an example of an imaging system 700 that includes an imager 702b that is In other embodiments, a second imager is used for the wearer's other eye 302 so that each eye is individually imaged. Imager 702b may include an infrared digital camera that is sensitive to infrared radiation. The imager 702b is mounted so that it faces forward (in the direction of the wearer's vision), rather than facing backward and directed to the eye 304 (as in camera 500 shown in FIG. 6). By placing imager 702b closer to the wearer's ear, the weight of imager 702b is also closer to the ear, making the imager retro-facing and closer to the front of the HMD (e.g., closer to display 62 in FIG. 2). ), this HMD may be easier to wear. Also, by placing the forward-looking imager 702b near the wearer's temples, the distance of the imager from the wearer's eye 304 is reduced compared to a backward-looking imager placed near the front of the HMD (e.g., shown in FIG. 4). compared to the camera 500), which is approximately twice as large. Since the depth of field of the image is approximately proportional to this distance, the depth of field for the forward imager 702b is approximately twice as large as for the backward imager. A larger depth of field for imager 702b may be advantageous for imaging the eye region of a wearer with large or protruding noses, brow ridges, and the like.

[0197] The imager 702b is positioned to view the inner surface 704 of an otherwise transparent optical element 706. The optical element 706 may be part of the HMD's display 708 (or the lens of a pair of glasses). Optical element 706 may transmit at least 10%, 20%, 30%, 40%, 50% or more of visible light incident on the optical element. In other embodiments, the optical element 706 need not be transparent (eg, in a virtual reality display). Optical element 706 may include a CLC off-axis mirror 708 . The CLC off-axis mirror 708 can be a surface that reflects a first wavelength range while being substantially transmissive to a second wavelength range (ie, different from the first wavelength range). The first wavelength range can be in the infrared and the second wavelength range can be in the visible. For example, the CLC off-axis mirror 708 may include a hot mirror that transmits visible light and reflects infrared light. In these embodiments, infrared rays 710a, 712a, and 714a from the wearer propagate to and reflect off optical element 706, resulting in reflected infrared rays 710b, 712b that can be imaged by imager 702b. , 714b). In some embodiments, imager 702b is configured to include at least a subset (eg, a non-empty subset and/or all) of the first wavelength range reflected by CLC off-axis mirror 708. It may be sensitive enough to capture a smaller subset) or capable of capturing it. For example, the CLC off-axis mirror 708 may reflect infrared light in the range of 700 nm to 1.5 μm, and the imager 702b may be sensitive enough to capture or capture near infrared light at wavelengths between 700 nm and 900 nm. . As another example, the CLC off-axis mirror 708 can reflect infrared radiation in the range of 700 nm to 1.5 μm, and the imager 702b can include a filter that filters infrared radiation in the range of 900 nm to 1.5 μm, Allows imager 702b to capture near infrared light at wavelengths between 700 nm and 900 nm.

[0198] Visible light from the outside world 1144 (FIG. 6) is transmitted through the optical element 706 and can be perceived by the wearer. In effect, the imaging system 700 shown in FIG. 24A acts as if there is a virtual imager 702c directed back towards the eye 304 of the wearer. The virtual imager 702c can image virtual infrared rays 710c, 712c, 714c (shown as dotted lines) propagating from the wearer's eye 704 through the optical element 706. A hot mirror (or other DOE described herein) may be disposed on the inner surface 704 of the optical element 706, but this is not a limitation. In other embodiments, a hot mirror or DOE may be disposed on an external surface of the optical element 706 or within the optical element 706 (eg, a volume HOE).

[0199] FIG. 24B schematically illustrates another example of an imaging system 700. In this embodiment, perspective distortion may be reduced or eliminated by using an accommodation control lens assembly 716b (eg, a shift lens assembly, a tilt lens assembly, or a tilt-shift lens assembly) with the imager 702b. In some embodiments, the accommodation control lens assembly 716b may be part of the lens of the imager 702b. The perspective control lens 716b can be configured so that the normal to the imager 702b is substantially parallel to the DOE (or HOE) or the normal to the region of the surface 704 that includes the hot mirror. In effect, the imaging system 700 shown in FIG. 24B acts as if there is a virtual imager 702c having a virtual accommodation control lens assembly 716c directed back towards the wearer's eye 304.

[0200] Additionally or alternatively, as shown schematically in FIG. 24C, the CLC off-axis mirror 708 of the optical element 706 has, on its surface 704, the reflected light 710b, It may have an off axis holographic mirror (OAHM) used to reflect light 710a, 712a, 714a to facilitate viewing of eye 304 by camera imager 702b capturing 712b, 714b. . The OAHM 708 may also have optical power, in which case it may be an off-axis volumetric diffractive optical element (OAVDOE), as schematically shown in FIG. 24D. In the example shown in FIG. 24D, the effective position of virtual camera 702c is at infinity (and not shown in FIG. 24D).

[0201] In some embodiments, a HOE (eg, OAHM or OAVDOE) may be divided into multiple segments. Each of these segments can have different optical properties or characteristics, including, for example, reflection angles at which the segments reflect incoming (infrared) light or optical power. The segments can be configured such that light is reflected from each segment towards the imager 702b. Consequently, the image acquired by imager 702b will also be divided into a corresponding number of segments each effectively viewing the eye from a different angle. 24E shows a display system with OAHM having three segments 718a1 , 718a2 , 718a3 each acting as a respective virtual camera 702c1 , 702c2 , 702c3 imaging the eye 304 at a different angular position. An example of 700 is schematically illustrated.

[0202] Figure 24F schematically illustrates another example of a display system 700 with an OAHM having three segments 718a1, 718a2, 718a3 each with an optical power (e.g., segmented OAVDOE) , each segment creates an infinite virtual camera imaging the eye 304 at a different angular position. Three segments are schematically illustrated in FIGS. 24E and 24F , but this is for illustration and not limitation. In other embodiments, 2, 4, 5, 6, 7, 8, 9 or more segments may be utilized. None, some or all of these segments of the HOE may have optical power.

[0203] Three segments 718a1, 718a2, 718a3 are shown spaced horizontally across optical element 706 in FIGS. 24E and 24F. In other embodiments, the segments may be vertically spaced on optical element 706 . 24G schematically depicts DOE 718 having two vertically spaced segments 718a1 and 718a2, segment 718a1 being in the same general horizontal plane as imager 702b (segment 718a1). segment 718a2 is configured to reflect light upwardly towards imager 702b. Similar to bifocal lenses, the arrangement shown in FIG. 24G is the imaging system 700 obtained by the imager 702b from the upper segment 718a1 when the wearer looks forward through the upper portion of the HMD. 718a2 uses reflected imagery from the sub-segment 718a2 when the wearer looks downward at the lower portion of the HMD (shown schematically through the dashed arrow). It can be advantageous in enabling

[0204] A mixture of horizontally spaced and vertically spaced segments may be used in other embodiments. For example, FIG. 24H shows another example of an HOE 718 having a 3x3 array of segments each containing a CLC off-axis mirror. Imager 702b may obtain reflection data from each of these nine segments representing rays emanating from different areas and angular directions from the eye region. Two example rays propagating from the eye region to HOE 718 and reflecting back to imager 702b are shown as solid and dashed lines. Imaging system 700 (or processing module 224 or 228) analyzes the reflection data from the plurality of segments to multiscopically determine the three-dimensional shape of the eye or gaze direction of the eye (eg, eye pose). ) can be calculated.

[0205] Embodiments of an optical system 700 that utilize segments may have multiple benefits. For example, segments may be used individually by selecting particular segments that are best suited for a particular task, or segments may be used collectively to multisterically estimate the three-dimensional shape or pose of the eye. In the former case, this selectivity can be used to select the image of the wearer's iris with the least occlusion, eg by eyelids or eyelashes. In the latter case, a three-dimensional reconstruction of the eye may be used to estimate orientation (e.g., by estimation of the location of corneal dilatation) or accommodation (e.g., by estimation of lens-induced distortion on the apparent location of the pupil). can

Polarization converters based on notch reflectors

[0206] To realize a wide-field display, the focus of virtual images must be adjusted to resolve the dislocation-accommodation conflict. Variable focus lenses may be placed to change the focus of virtual images between the display and the user's eyes. However, while most variable/switchable focus lenses are polarization sensitive, projected virtual images may not be properly polarized. Such displays may require polarization insensitive lenses (often paired lens sets) or polarizers (>50% reduction in brightness due to loss of light in the non-transmissive polarization). Efficient conversion of virtual image polarization is required to manufacture compact/light-efficient variable focus light-field displays.

[0207] To create virtual images in augmented reality displays, multiple narrow-band sources (eg, red, green, blue (RBG) LEDs or lasers) are often used. A waveguide-based display system can be constructed with diffractive optical elements to project images to the eyes of a user. A projected image often does not preserve polarization purity even when the image's well-defined polarization is injected into the waveguide.

[0208] As described herein, a notch reflector generally refers to a light reflector that transmits light at most wavelengths substantially unaltered, but reflects light within a specific range of wavelengths with relatively high efficiency. The specific range of wavelengths from which light is reflected is referred to as a “notch”. Notch reflectors are sometimes also referred to as narrowband reflectors. The wavelength range at the notch may be a different range including, for example, <10 nm, <50 nm, <100 nm, <250 nm, or a range defined by any two of these values. Notch reflectors can be formed from multiple dielectric layers (multilayers), liquid crystals, metamaterials, metastructures, and the like. Notch reflectors may include diffractive optical elements, surface or volumetric holograms, and the like. Notch reflectors may be laminated onto a substrate material (eg, polymer or glass). In most of the implementations described herein, to reflect RGB light, a reflector includes multiple notch reflectors, the notch of each reflector being tuned to one of the specific RGB colors (e.g., the reflector is an R-notch reflector, including G-notch and B-notch reflectors). Thus, the wavelength range of each notch may match the wavelength range of light injected into the display (e.g., the R-notch matches the wavelength range of red light injected by a red LED or laser, and the G and B notches match the wavelength range of red light injected by a red LED or laser). The same applies).

[0209] Various embodiments described herein include a notch reflector that includes a transmissive substrate, such as a polished glass or polymeric substrate, on which one or more active layers are formed. As described herein, the active layer includes a layer or coating configured to provide one or more of the notch reflective properties described herein. The one or more active layers have a wavelength range (Δλ) of about 50 nm, about 70 nm, about 100 nm about 150 nm, or in a range less than any of these values or in a range defined by any two of these values. configured to notch-reflect light, wherein the wavelength is red light comprising light of one or more wavelengths in the range of about 620-780 nm, green light comprising light of one or more wavelengths in the range of about 492-577 nm, or about 435-780 nm. It is focused around blue light comprising light of one or more wavelengths in the 493 nm range. In some embodiments, the wavelength range Δλ may substantially cover a red light range of about 620-780 nm, a green light range of about 492-577 nm, or a blue light range of about 435-493 nm.

[0210] Various embodiments described herein include a notch reflector configured as a polarizing notch reflector. Within the notch-reflecting range, the polarizing notch reflector substantially reflects light having the opposite polarity while substantially allowing light having one polarity to pass through. For example, when light having both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) within the notch reflection range is incident on the polarization notch reflector, the notch reflector , can substantially transmit light having an opposite one of RHCP and LHCP while reflecting light having substantially one of RHCP and LHCP. Similarly, when light having both linear vertical polarization (LVP) and linear horizontal polarization (LHP) is incident on the polarization notch reflector, the notch reflector substantially reflects light having one of the LVP and LHP, while the LVP and LHP can substantially pass light having the opposite one.

[0211] Various embodiments described herein include a notch reflector configured as a non-polarizing notch reflector. Within the notch reflection range, a non-polarizing notch reflector substantially reflects light incident on it regardless of its polarization. For example, when light having both LHCP and RHCP within the notch reflection range is incident on a non-polarizing notch reflector, the notch reflector may substantially reflect light having both RHCP and LHCP. Similarly, when light having both the LVP and LHP is incident on the polarizing notch filter, the notch filter can substantially reflect the light having both the LVP and LHP.

[0212] In various embodiments described herein, a notch reflector configured as a polarizing or non-polarizing notch reflector may also be independently configured as a polarization-converting notch reflector. Within the notch-reflection range, upon reflection of light having polarization, the polarization-converting notch reflector converts the polarization of the reflected light to the opposite polarity. For example, when light having one of LHCP and RHCP within the notch reflection range is incident on the polarization-converting notch reflector, the notch reflector converts one of RHCP and LHCP to the opposite one of RHCP and LHCP. Similarly, when light having one of LVP and LHP is incident on the polarization converting notch reflector, the notch reflector converts one of LVP and LHP to the opposite one of LVP and LHP.

[0213] As described herein, a notch reflector configured to reflect light having one or more polarizations, within a notch reflection range, may be configured to reflect substantially all of the light having one or more polarizations incident on it. For example, when the notch reflector is configured to reflect light having one or both of the RHCP and LHCP, the notch reflector may absorb, for example, more than 80%, more than 90% of the light having one or both of the RHCP and LHCP incident on it, reflect greater than 95%, greater than 99%, greater than 99.99%, greater than 99.999%, or greater than 99.9999%. On the other hand, when the notch reflector is configured to reflect light having one but the other of RHCP and LHCP, the notch reflector, for example, absorbs more than 80%, 90% of the light having but one of RHCP and LHCP incident on it. may reflect greater than 95%, greater than 99%, greater than 99.99%, greater than 99.999%, or greater than 99.9999%. Conversely, a notch reflector is configured so that unreflected light, e.g., light having a wavelength outside the notch reflection range (Δλ) or a polarization the notch reflector is not configured to reflect is substantially completely transmitted, e.g., 80% of the light incident on it. More than 90%, more than 95%, more than 99%, more than 99.99%, more than 99.999%, or more than 99.9999% may be permeable.

[0214] In some display devices described herein, it may be desirable to recycle some light that is outcoupled from the waveguide. For example, a waveguide may outcouple light having more than one polarization, but an optical element configured to exert an optical function, such as an optical force, on the outcoupled light prior to being viewed by a user such as: A lens, such as a transmissive or reflective lens, may be polarization-selective. Under some circumstances, light having a polarization for which an optical element is not configured to exert an optical function may be transmitted without being viewed by a user. For example, a lens coupled to a waveguide exerts an optical power on light having a polarization, e.g., one of RHCP or LHCP, due to the lack of matching between the polarization handiness of the incident elliptically or circularly polarized light and the direction of rotation of the chiral structures of the CLCG. , while transmitting light having a different polarization, eg, the other one of RHCP or LHCP. In such situations, it may be desirable to recycle the light having the remaining one of RHCP or LHCP to provide the viewing experience to the user with a higher brightness. To address these and other needs, various embodiments of wave-guiding devices that use one or more polarization converting reflectors are disclosed below to address these needs.

Exemplary Circular Polarization Conversion Display Devices

[0215] FIG. 25A illustrates a display device 2500A configured to output image information to a user. The display device 2500A includes a waveguide assembly 2504, also referred to as an eyepiece, interposed between a non-polarizing notch reflector 2508 and a polarizing notch reflector 2512. In various embodiments, waveguide assembly 2504 can be configured in a manner similar to waveguide assembly 1178 described above with respect to FIG. 6 . Similar to the configuration described above with respect to FIG. 6 , in operation, display device 2500A is positioned between world 1114 and eye 4 so that eye 4 is drawn from display device 2500A as well as the world. Light is received from 1114.

[0216] In particular, in various embodiments described herein, the waveguide assembly 2504 of the display device 2500A is configured to propagate light within each individual waveguide by total internal reflection (TIR) in the x-direction. Each includes one or more waveguides (eg, 1182, 1184, 1186, 1188, and 1190 of FIG. 6). Light propagating generally in the x-direction is configured to extract light from the waveguide by redirecting light propagating within each individual waveguide out of the waveguide to output image information to the eye 4, for example in the z-direction. - It may be output using coupling optical elements or light extraction optical elements (eg, 1282, 1284, 1286, 1288, and 1290 of FIG. 6). In various embodiments, although not shown for clarity, the waveguide assembly 2504 can include any of CLCGs formed from one or more CLC layers configured as out-coupling optical elements as described above. Various other details of the waveguide assembly 2504 described above are omitted herein.

[0217] Referring still to FIG. 25A, a non-polarizing notch reflector 2508 according to various embodiments described herein is, within the notch-reflective range, the non-polarizing notch reflector 2508 related to its polarization. It is configured to substantially reflect light incident thereon without Also, in the illustrated embodiment, the non-polarization reflector is configured as a polarization-converting notch reflector such that the polarization-converting notch reflector, upon reflection of light having a polarization within the notch-reflection range, converts the polarization of the reflected light to the opposite polarity. convert to Non-polarizing notch reflector 2508 includes a notch reflector comprising a transmissive substrate, such as a polished glass or polymeric substrate, on which one or more active layers are formed. In some embodiments of the notch reflectors described herein, one or more active layers formed on a substrate can include one or more dielectric coatings, the combination of which results in the various notch-reflective properties described above.

[0218] Referring still to FIG. 25A, a polarizing notch reflector 2512 according to various embodiments described herein is provided, within a notch-reflecting range, in which the polarizing notch reflector 2512 is incident on it in a polarization-selective manner. configured to substantially reflect light. Also, in the illustrated embodiment, the polarizing reflector 2512 is configured such that, unlike the non-polarizing notch reflector 2508, the polarizing notch reflector 2512 is not configured as a polarization converting notch reflector, so that upon reflection of light having a polarization , the polarization notch reflector 2512 does not convert the polarization of the reflected light to the opposite polarity. Polarization notch reflector 2512 includes a notch reflector comprising a transmissive substrate, such as a polished glass or polymeric substrate, on which one or more active layers are formed. In some embodiments of the notch reflectors described herein, the one or more active layers formed on the substrate may include one or more cholesteric liquid crystal (CLC) layers. The one or more active layers formed on the substrate may include one or more cholesteric liquid crystal (CLC) layers described according to various embodiments described above.

[0219] Still referring to FIG. 25A, in the following the display device 2500A in operation is further described. As described above, some of the light propagating in the x-direction within one or more waveguides in waveguide assembly 2504 may be redirected or out-coupled in the z-direction. In the illustrated embodiment, the light out-coupled from the waveguide assembly 2504 includes circularly polarized light beams (2516-L with LHCP and 2516-R with RHCP). Light beams 2516-L with LHCP and 2516-R with RHCP, for example, travel in the positive z-direction until they impinge on the surface of polarization notch reflector 2512 .

[0220] The polarization notch reflector 2512 is a CLC layer having chiral structures similar to those described above, such as chiral structures 1012-1, 1012-2, ... 1012-i described above with respect to FIG. (1004). In operation, when an incident light having a combination of light beams having a leftward circular polarization and light beams having a rightward circular polarization is incident on the surface of the polarization notch reflector 2512, by Bragg-reflection, one circular polarization handed Light with varnish is reflected by the CLC layer 1004, while light with the opposite polarization handiness is transmitted through the CLC layer 1008 without substantial interference. As explained herein and throughout this disclosure, handyness is defined as viewed in the direction of propagation. According to embodiments, the direction of polarization or the handiness of polarization of light beams 2516-L and 2516-R is matched so that it is a liquid crystal of chiral structures 1012-1, 1012-2, ... 1012-i. Incident light is reflected when it has the same rotational direction as the molecules. As illustrated, light beams 2516 -L having left circular polarization and light beams 2516 -R having right circular polarization are incident on the surface of CLC layer 1004 . In the illustrated embodiment, the liquid crystal molecules of the chiral structures 1012-1, 1012-2, ... 1012-i move in the direction in which the incident light beams 2516-L, 2516-R travel, eg positive x. It is continuously rotated from the -direction to the clockwise direction, which is the same direction of rotation as light beams 1016-L having leftward circular polarization. As a result, light beam 2516-L having rightward circular polarization is substantially reflected from polarizing notch reflector 2512, while light beam 2516-R having rightward circular polarization is substantially reflected from polarizing notch reflector 2512. permeates through

[0221] The light beam 2516-L out-coupled from the CLC layer 1004 and having the LHCP is a light beam 2520-L having the same polarization as the light beam 2516-L, which is a polarization notch reflector ( 2512). The resulting light beam 2520-L is reflected from the light beam 2520-L with LHCP by the non-polarizing notch reflector 2508, due to the polarization-converting properties of the non-polarizing notch reflector 2508. It propagates towards the non-polarizing notch reflector 2508 until it is substantially reflected as a light beam 2520-R having a polarization handiness, e.g., RHCP, of The resulting light beam 2520 -R with RHCP is substantially transmitted through the CLC layer 1004 and further through the polarization notch reflector 2512 to enter the eye 4 . Summarizing and still referring to FIG. 25A , one polarization (eg, , right-handed circular polarization (RHCP) light beam 2516-R is transmitted through polarization notch reflector 2512, while light with orthogonal polarization (e.g., left-handed circular polarization (LHCP)) ( 2516-L) is reflected toward world 1114 as light beam 2520-L. Another notch reflector, a non-polarizing notch reflector 2508 (e.g., a multilayer notch reflector), is disposed between the world 1114 and the waveguide assembly 2504 and directs light beam 2520-L as light beam 2520-R. It is configured to reflect back to the user's eyes. Because the polarizing notch reflector 2512, such as a CLC notch reflector, does not convert the polarization of the light reflected therefrom, whereas a non-polarizing notch reflector, such as a multilayer reflector, converts the polarization of the light reflected therefrom, the light beam 2516-R may also be transmitted through the polarization notch reflector 2512 as shown. It will be appreciated that both notch reflectors 2512 and 2508 (e.g., CLC and multilayer) can be designed to reflect only light sources for virtual images to minimize impact on images of world 1114. .

Exemplary Linear Polarization Conversion Display Devices

[0222] FIG. 25B illustrates a display device 2500B configured to output image information to a user. Similar to display device 2500A illustrated above with respect to FIG. 25A, display device 2500B is a waveguide assembly sandwiched between a non-polarizing notch reflector 2508 and a polarizing notch reflector 2514, such as a linearly polarizing notch reflector. (2504). The waveguide assembly 2504 and the non-polarizing notch reflector 2508 are constructed in a manner similar to that described above with respect to FIG. 25A and thus are not described in detail herein.

[0223] Still referring to FIG. 25B, similar to the polarizing notch reflector 2512 described above with respect to FIG. 25A, the polarizing notch reflector 2514 in the illustrated embodiment is, within the notch-reflecting range, a notch reflector. 2514 is configured to substantially reflect light incident upon it in a polarization-selective manner. Also, in the embodiment illustrated above, the polarizing reflector 2514 is configured such that, unlike the non-polarizing notch reflector 2508, the polarizing reflector 2514 does not convert the polarization of the reflected light to the opposite polarity.

[0224] However, unlike the polarizing notch reflector 2512 described above with respect to FIG. 25A, the polarizing notch reflector 2514 in the illustrated embodiment is configured such that the polarizing notch reflector 2514 does not include a CLC layer. . Instead, polarization notch reflector 2514 includes a notch reflector comprising a transmissive substrate, such as a polished glass or polymeric substrate, on which one or more active layers are formed. In some embodiments of the notch reflectors described herein, one or more active layers formed on a substrate can include one or more dielectric coatings, the combination of which results in the various notch-reflective properties described above.

[0225] Still referring to FIG. 25B, the display device 2500B further includes a quarter-wave plate 2510 interposed between the non-polarizing notch reflector 2508 and the waveguide assembly 2504.

[0226] Still referring to FIG. 25B, in the following the display device 2500B in operation is further described. As described above, some of the light propagating in the x-direction within one or more waveguides in waveguide assembly 2504 may be redirected or out-coupled in the z-direction. In the illustrated embodiment, the light out-coupled from the waveguide assembly 2504 includes linearly polarized light beams (2516-V with LVP and 2516-H with LHP). The light beams (2516-V with LVP and 2516-H with LHP) travel in the positive z-direction, eg, until the beams impinge on the surface of polarization notch reflector 2514. As a result, light beam 2516-V with LVP is substantially reflected from polarizing notch reflector 2514, while light beam 2516-H with LHP is substantially transmitted through polarizing notch reflector 2514. .

[0227] The light beam 2516-V out-coupled from the waveguide assembly 2504 and having the LVP is a light beam 2520-V having the same polarization as the light beam 2516-V, which is a polarization notch reflector ( 2514). The resulting light beam 2520-V with LVP propagates toward the quarter-wave plate 2510 and is transmitted through the quarter-wave plate 2510, polarizing the non-polarizing notch reflector 2508. -because of its conversion properties, it is reflected from the non-polarizing notch reflector 2508 and further through the quarter-wave plate 2510 as a light beam 2520-H having an opposite polarization handyness, e.g., LHP permeates The resulting light beam 2520-H with the LHP is substantially transmitted through the polarizing notch reflector 2514.

[0228] Summarizing and still referring to FIG. 25B , instead of the CLC-containing polarization notch reflector 2512 (FIG. 25A), it reflects one linear polarization (e.g., linear vertical polarization (LVP)) for certain wavelengths. By placing a polarizing notch reflector 2514 and further placing a quarter-wave plate 2510 interposed between the non-polarizing notch reflector 2508 and the waveguide assembly 2504, the non-polarizing notch reflector 2508 ) becomes orthogonal (eg, linear horizontal polarization (LHP)) as shown. Similar to the CLC-containing notch reflector described above with respect to FIG. 25A, the polarization of the projected virtual image is converted to one linear polarization in an efficient manner (eg, approaching 100% efficiency).

Variable-focus virtual imaging systems based on polarization converters

Exemplary Linear Polarization Variable-Focus Lenses

[0229] Figures 26A and 26B illustrate display devices 2600A, 2600B configured to output image information to a user. Display devices 2600A and 2600B are structurally identical. Display device 2600A is used herein to describe outputting virtual images to a user, while display device 2600B is used herein to describe outputting real-world images to a user.

[0230] Display device 2600A/2600B includes the various components of display device 2500A described above with respect to FIG. 25A, further including additional optical components for focusing and converting light output therefrom. . Similar to the display device 2500A illustrated above with respect to FIG. 25A, the display device 2600A/ 2600B includes a waveguide assembly 2504 sandwiched between a non-polarizing notch reflector 2508 and a polarizing notch reflector 2512. include Waveguide assembly 2504, non-polarizing notch reflector 2508 and polarizing notch reflector 2512 are constructed in a similar manner to that described above with respect to FIG. 25A and, therefore, are not described in further detail herein.

[0231] The display device 2600A/2600B additionally includes a first 1/2 formed on the outer sides of a non-polarizing notch reflector 2508, such as a multilayer notch reflector and a polarizing notch reflector 2512, such as a CLC notch reflector. A first comprising a 4-wave plate (QWP 1) 2604 and a second quarter-wave plate (QWP 2) 2608 formed on outer sides of the QWP 1 2504 and QWP 2 2608 A linear polarization lens (L1) 2612 and a second linear polarization lens (L2) 2616 are further included. In various embodiments, one or both of L1 and L2 may be switchable lenses, which may be switchable, such as by application of an electric field, voltage or current. Also, one or both of L1 and L2 may have variable focal intensities or focal depths, the focal intensities and focal depths of which may be controlled, for example, by application of an electric field, voltage or current.

[0232] Referring to Fig. 26A, a display device 2600A is used herein to describe outputting a virtual image to a user. As described above with respect to FIG. 25A , a portion of light propagating in the x-direction within one or more waveguides in waveguide assembly 2504 may be redirected or out-coupled in the z-direction. In the illustrated embodiment, the light out-coupled from the waveguide assembly 2504 includes circularly polarized light beams (2516-L with LHCP and 2516-R with RHCP). Light beams 2516-L with LHCP and 2516-R with RHCP, for example, travel in the positive z-direction until they impinge on the surface of polarization notch reflector 2512 . Due to the CLC layer 1004 included in the polarizing notch reflector 2512, the light beam 2516-L having a right-hand circular polarization is substantially reflected from the polarization notch reflector 2512, while the light beam having a right-hand circular polarization (2516-R) is substantially transmitted through polarization notch reflector 2512.

[0233] The light beam 2516-L out-coupled from the CLC layer 1004 and having the LHCP is a light beam 2520-L having the same polarization as the light beam 2516-L, which is a polarization notch reflector ( 2512). The resulting light beam 2520-L is reflected from the light beam 2520-L with LHCP by the non-polarizing notch reflector 2508, due to the polarization-converting properties of the non-polarizing notch reflector 2508. It propagates towards the non-polarizing notch reflector 2508 until it is substantially reflected as a light beam 2520-R having a polarization handiness, e.g., RHCP, of The resulting light beam 2520 -R with the RHCP is transmitted through the polarizing notch reflector 2512 having the substantially CLC layer 1004 .

[0234] Upon exiting polarization notch reflector 2512, light beams 2516-R and 2520-R with RHCP are further transmitted through QWP 2 2608, which is circularly polarized light beams 2516-R and 2520-R) into linearly polarized light beams 2520-H and 2516-H, respectively. After exiting QWP 2 (2608), light beams 2520-H and 2516-H are further transmitted through L2 (2616). When activated, L2 2616 focuses or defocuss light beams 2520-H and 2516-H into focused output light beams 2620 prior to viewing by eye 4.

[0235] In summary, the illustrated embodiment of FIG. 26A is an example of a waveguide-based projection display with variable focus/switchable lenses configured to operate on light having linear polarization (eg, LHP in the illustrated embodiment). shows Thus, the polarization of light in the virtual images is converted to have one of the circular polarizations (e.g., RHCP in FIG. 26A) as the light passes through polarization notch reflector 2512, e.g. is further converted to have one of the linear polarizations (e.g., LHP in FIG. 26A) by The focus of the virtual image is controlled by L2 2616 as shown in FIG. 26A.

[0236] Referring to FIG. 26B, display device 2600B is used herein to describe outputting an image of world 1114 to a user. As illustrated, incident light beams 2632-H and 2624-V, each having LHP and LVP, enter and are transmitted through L1 2612, respectively. Upon exiting L1 2612, light beams 2632-H and 2624-V pass through QWP 1 2604, which separates light beams 2632-R and 2624-L with RHCP and LHCP respectively. ) to each conversion. Light beams 2632-R and 2624-L are subsequently transmitted through non-polarizing notch reflector 2508, waveguide assembly 2504, polarizing notch reflector 2512, and QWP 2 2608, and thus, respectively re-converts the light beams of L into light beams 2636-H and 2628-V having LHP and LVP, respectively. Light beams 2636-H and 2628-V are then transmitted through L2 2616, thus outputting respective light beams 2636 and 2628, respectively.

[0237] To output a real world image, lenses L1 2612 and L2 2616 are configured to operate on light having one of the linear polarizations but not the other. Consequently, in the illustrated embodiment, one of the incident light beams 2632-H and 2624-V, e.g., light beam 2632-H with the LHP, is transmitted by lenses L1 2612 and L2 2616. Not affected.

[0238] L1 2612 and L2 2616 may be configured to have opposite lensing effects or optical powers for light passing through them. For example, if L1 2612 is configured to have a focusing lens effect, L2 2616 can be configured to have a defocusing effect so that opposite lens effects negate each other. Accordingly, the remaining one of incident light beams 2632-H and 2624-V, e.g., light beam 2632-V having LVP, upon passing through L1 2612, is subject to a lensing effect, e.g., focusing, by L1 2612. or undergo defocusing. However, after conversion to light beam 2624-L with LHCP and back to light beam 2628-V with LVP, the lensing effect of L1 2612 is reduced by L2 2616 with the opposite lensing effect. invalidated Thus, since there are two quarter-wave plates (QWP 1 2604, QWP 2 2608) whose optical retardation effects negate each other, and two lenses whose lens effects negate each other Because (L1 2612 and L2 2616) are present, the image of the world 1114 as viewed by eye 4 is substantially unaffected, as described above with respect to FIG. 26B. On the other hand, the virtual image may be influenced by L2 (2616).

[0239] As described above, a polarization conversion similar to that performed using display device 2500A (FIG. 25A) having a polarization notch reflector 2512 that includes a CLC layer 1004 also does not include a CLC layer. This can be done using a display device 2500B (FIG. 25B) having a polarization notch reflector 2514 that does not have a polarization. Accordingly, FIGS. 26C and 26D illustrate display devices 2600C and 2600D configured to output image information to a user, where the display devices 2600C and 2600D include a polarizing notch reflector 2514 that does not include a CLC layer. have Display devices 2600C and 2600D are structurally identical. Display device 2600C is used herein to describe outputting virtual images to a user, whereas display device 2600D is used herein to describe outputting real world images to a user.

[0240] Similar to the display device 2500B illustrated above with respect to FIG. 25B, the display device 2600C/2600D is a waveguide assembly sandwiched between a non-polarizing notch reflector 2508 and a polarizing notch reflector 2514 ( 2504). The waveguide assembly 2504 and the non-polarizing notch reflector 2508 are configured in a manner similar to that described above with respect to FIG. 25A and thus are not described in further detail herein.

[0241] Still referring to FIG. 26C, in a manner similar to that described above with respect to FIG. 25B, the polarization notch reflector 2514 in the illustrated embodiment is within the notch-reflecting range, so that the notch reflector 2514 is polarizing. - configured to substantially reflect light incident on it in a selective manner. Also, in the embodiment illustrated above, the polarizing reflector 2514 is configured such that, unlike the non-polarizing notch reflector 2508, the polarizing reflector 2514 does not convert the polarization of the reflected light to the opposite polarity.

[0242] Still similar to the description above with respect to FIG. 25B, the polarizing notch reflector 2514 of the display device 2600C/2600D in the illustrated embodiment is configured such that the polarizing notch reflector 2514 does not include a CLC layer. do. The display device 2600C/2600D also includes a second quarter-wave plate (QWP 1 2510) interposed between the non-polarizing notch reflector 2508 and the waveguide assembly 2504.

[0243] Display device 2600C/2600D additionally includes a non-polarizing notch reflector 2508, e.g., a first quarter-wave plate (QWP) formed on the left side (world 1114 side) of the multilayer notch reflector. 1) 2604, wherein a first linear polarization lens (L1) 2612 and a second linear polarization lens (L2) 2616 formed on the outer sides of the QWP 1 2504 and the polarization notch reflector 2514, respectively. ) is further included. In various embodiments, one or both of L1 and L2 may be switchable lenses, which may be switchable, such as by application of an electric field, voltage or current. Also, one or both of L1 and L2 may have variable focal intensities or focal depths, the focal intensities and focal depths of which may be controlled, for example, by application of an electric field, voltage or current.

[0244] Referring to Fig. 26C, a display device 2600C is used herein to describe outputting a virtual image to a user. As described above with respect to FIG. 25B , a portion of light propagating in the x-direction within one or more waveguides in waveguide assembly 2504 may be redirected or out-coupled in the z-direction. In the illustrated embodiment, the light out-coupled from the waveguide assembly 2504 includes linearly polarized light beams (2516-V with LVP and 2516-H with LHP). The light beams (2516-V with LVP and 2516-H with LHP) travel in the positive z-direction, eg, until the beams impinge on the surface of polarization notch reflector 2514. As such, light beam 2516-V with LVP is substantially reflected from polarizing notch reflector 2514, while light beam 2516-H with LHP is substantially transmitted through polarizing notch reflector 2514.

[0245] The light beam 2516-V out-coupled from the waveguide assembly 2504 and having the LVP is a light beam 2520-V having the same polarization as the light beam 2516-V, which is a polarization notch reflector ( 2514). The resulting light beam 2520-V with LVP propagates toward the quarter-wave plate 2510 and is transmitted through QWP2 2510, resulting in the polarization-converting properties of the non-polarizing notch reflector 2508. , is reflected from the non-polarizing notch reflector 2508 and is further transmitted through QWP2 2510 as light beam 2520-H having the opposite polarization handiness, e.g., LHP. The resulting light beam 2520-H with the LHP is substantially transmitted through the polarizing notch reflector 2514.

[0246] Upon exiting polarization notch reflector 2514, light beams 2516-V and 2516-H with LHP are further transmitted through L2 2616. When activated, L2 focuses or defocuses light beams 2520-H and 2516-H into focused output light beams 2620 prior to viewing by eye 4.

[0247] Referring to FIG. 26D, display device 2600D is used herein to describe outputting an image of world 1114 to a user. As illustrated, incident light beams 2632-H and 2624-V, each having LHP and LVP, enter and are transmitted through L1 2612, respectively. Upon exiting L1 2612, light beams 2632-H and 2624-V pass through QWP 1 2604, which converts the respective light beams into light beams with RHCP and LHCP, respectively. Light beams 2632-R and 2624-L are subsequently transmitted through non-polarizing notch reflector 2508 and then transmitted through QWP 2 2510, which converts light beams with RHCP and LHCP to LHP and light beams 2636-H and 2628-V with LVP, respectively. Light beams 2636-H and 2628-V are then transmitted through the waveguide assembly 2504, then through the polarization notch reflector 2514, then through L2 2616, and so on, respectively outputs light beams 2636 and 2628, respectively.

[0248] Similar to the display device described above with respect to FIGS. 26A/26B, the lenses L1 2612 and L2 2616 operate on light having one of the linear polarizations but not on the other. configured so as not to Consequently, in the illustrated embodiment, one of the incident light beams 2632-H and 2624-V, e.g., light beam 2632-H with the LHP, is transmitted by lenses L1 2612 and L2 2616. Not affected.

[0249] Also, similar to the display device described above with respect to FIGS. 26A/26B, two quarter-wave plates (QWP 1 2604), QWP 2 ( 2608) is present, and because there are two lenses (L1 2612 and L2 2616) whose lens effects cancel each other out, as described above with respect to FIG. 26C, the eye 4 The image of the world 1114 as viewed by ) is substantially unaffected, while the virtual image is affected by L2 2616.

[0250] In summary, in the embodiment illustrated in FIGS. 26C and 26D, a polarization conversion similar to that achieved using display devices 2600A/2600B having polarization notch reflectors including a CLC layer therein is shown in FIG. 26C. and using a polarizing notch reflector 2514, such as a linear polarizing notch reflector, instead of the polarizing notch reflector 2514 having CLC layers therein (FIG. 26A/26B), as shown in FIG. 26D. . To convert the polarization of the virtual images, QWP 2 2510 is placed between the non-polarizing notch reflector 2508 and the waveguide assembly 2504. Since the polarization notch reflector 2514, e.g., the linear polarization notch reflector, converts the virtual image polarization to linear polarization (e.g., LHP), another quarter-wave plate (QWP 1 2604) is used for compensation in L1 2612. ) and the non-polarizing notch reflector 2508.

Exemplary Circular Polarization Variable-Focus Lenses

[0251] Without wishing to be bound by any theory, when a light beam is taken along a closed cycle in the light's polarization states space, the dynamic phase can be obtained from the geometric phase as well as from the accumulated path lengths. The dynamic phase obtained from the geometric phase is due to local changes in polarization. In contrast, some optical elements based on geometric phase to form a desired phase front may be referred to as Pancharatnam-Berry phase optical elements (PBOEs). PBOEs can be composed of waveplate elements where the orientation of the fast axes depends on the spatial position of the waveplate elements. Applications of PBOEs include diffraction gratings such as blazed gratings, focusing lenses and axicons, among a variety of other applications.

[0252] Hereinafter, with reference to FIGS. 27A-27D, a variable that can be switched dynamically, e.g., by direct modulation of a Pancharatnam-Barry (PB) lens or by modulation of LC waveplates coupled to a static PB lens. Display devices using switchable lens elements or switchable lens assemblies that include PB phase lens elements are described. When multiple PB lens elements with different focal lengths are stacked, the overall focus of the lens stack can be switched between them by modulating the PB lenses or LC waveplates disposed between them. Advantageously, PB lenses can be configured to focus or defocus light having circular polarization. Consequently, the quarter-wave plate(s) included as part of display devices, e.g., display devices 2600A, 2600B, because the virtual image polarization is converted to circular polarization (e.g., RHCP) via the CLC reflector. may be omitted.

[0253] Figures 27A and 27B illustrate display devices 2700A, 2700B configured to output image information to a user. Display devices 2700A and 2700B are structurally identical. Display device 2700A is used herein to describe outputting virtual images to a user, while display device 2700B is used herein to describe outputting real-world images to a user.

[0254] The display device 2700A/2700B includes the various components of the display device 2600A/2600B described above with respect to FIGS. 26A and 26B, and additional optics for focusing and converting light output therefrom. contains more components. Similar to the display device 2600A/2600B illustrated above with respect to FIGS. 26A and 26B, the display device 2700A/2700B is a waveguide assembly sandwiched between a non-polarizing notch reflector 2508 and a polarizing notch reflector 2512. (2504). Waveguide assembly 2504, non-polarizing notch reflector 2508, and polarizing notch reflector 2512 are constructed in a similar manner to that described above with respect to FIGS. 26A and 26B, and thus are not described in further detail herein. don't

[0255] However, unlike display devices 2600A/2600B, in display devices 2700A/2700B, a non-polarizing notch reflector 2508, such as a multilayer notch reflector and a polarizing notch reflector 2512, such as a CLC notch reflector Quarter wave plates formed on the outer sides are omitted. Also, unlike display device 2600A/2600B, instead of linearly polarizing lenses, display device 2700A/2700B has first polarization formed on outer sides of non-polarizing notch reflector 2508 and polarizing notch reflector 2512, respectively. A 1 PB lens (PB L1) 2712 and a second PB lens (PB L2) 2716 are included. In various embodiments, one or both of PB L1 2712 and PB L2 2716 may be switchable lenses, which may be switchable, such as by application of an electric field, voltage or current. Additionally, one or both of PB L1 2712 and PB L2 2716 can have variable focal intensities, optical powers or focal depths that can be controlled, for example, by application of an electric field, voltage or current.

[0256] Referring to Fig. 27A, a display device 2700A is used herein to describe outputting a virtual image to a user. In operation, a portion of light propagating in the x-direction within one or more waveguides in waveguide assembly 2504 may be redirected or out-coupled in the z-direction, as described above with respect to FIG. 25A. The paths of the light beams out-coupled from the waveguide assembly 2504, including the circularly polarized light beams (2516-L with LHCP and 2516-R with RHCP), are the light beams 2516-R with RHCP and 2520-R) are the same as those described above with respect to FIG. 26A until transmitted through the polarizing notch reflector 2512 with the CLC layer 1004. Upon exiting polarization notch reflector 2512, light beams 2516-R and 2520-R with RHCP are further transmitted through PB L2 2716. When activated, PB L2 focuses or defocuses light beams 2520-H and 2516-H into focused output light beams 2620 prior to viewing by eye 4.

[0257] Referring to FIG. 27B, display device 2700B is used herein to describe outputting an image of world 1114 to a user. As illustrated, incident light beams 2632-R and 2624-L, with RHCP and LHCP, respectively, are sequentially formed by a non-polarizing notch reflector 2508, a waveguide assembly 2504, a polarizing notch reflector 2512, and a PB Light beams 2636-R and 2628-L transmitted through L2 2716 are transmitted through PB L1 2712. Unlike the display device 2600B illustrated above with respect to FIG. 26B, since there are no quarter-wave plates in the display device 2700, the light beams are circularly polarized light beams throughout the phase conversion and focusing. maintain. Light beams 2636-R and 2628-L are then transmitted through PB L2 2716, thus outputting respective light beams 2632 and 2628, respectively.

[0258] To output a real world image, lenses PB L1 2712 and PB L2 2716 are configured to operate on light having one of the circular polarizations but not the other. Consequently, in the illustrated embodiment, one of the incident light beams 2632-R and 2624-L, e.g., light beam 2624-L with an LHCP, is coupled to the lenses PB L1 2712 and PB L2 2716. ) is not affected by

[0259] PB L1 2712 and PB L2 2716 may be configured to have opposite lensing effects on light passing through them. For example, when PB L1 2712 is configured to have a focusing lens effect, PB L2 2716 can be configured to have a defocusing effect so that opposite lens effects negate each other. Consequently, the image of the world 1114 viewed by eye 4 is substantially unaffected, while the virtual image is affected by PB L2 2716, as described above with respect to FIG. 27A. .

[0260] As described above, a polarization conversion similar to that performed using display device 2500A (FIG. 25A) having a polarization notch reflector 2512 that includes a CLC layer 1004 also does not include a CLC layer. This can be done using a display device 2500B (FIG. 25B) having a polarization notch reflector 2514 that does not have a polarization. Accordingly, FIGS. 27C and 27D illustrate display devices 2700C and 2700D configured to output image information to a user, where the display devices 2700C and 2700D include a polarizing notch reflector 2514 that does not include a CLC layer. have Display devices 2600C and 2600D are structurally identical. Display device 2700C is used herein to describe outputting virtual images to a user, while display device 2700D is used herein to describe outputting real world images to a user.

[0261] Similar to the display device 2500B illustrated above with respect to FIG. 25B, the display device 2700C/2700D includes a waveguide assembly ( interposed between a non-polarizing notch reflector 2508 and a polarizing notch reflector 2514). 2504). The waveguide assembly 2504 and the non-polarizing notch reflector 2508 are configured in a manner similar to that described above with respect to FIG. 25A and thus are not described in further detail herein.

[0262] The display device 2700C/2700D additionally includes a first quarter-wave plate (QWP 1) formed between the non-polarizing notch reflector 2508, such as the multilayer notch reflector and the waveguide assembly 2504 ( 2604), and a second quarter-wave plate (QWP 2) 2510 formed between the polarization notch reflector 2514 and the second PB lens (PB L2) 2616. The display device 2700C/2700D further includes a first PB lens (PB L1) 2612 on the outer side of the non-polarizing notch reflector 2508. Accordingly, the display device 2700C/2700D is similar to the display device 2600C/2600D described with respect to FIGS. 26C and 27D except for the types of lenses and the relative positions of QWP 1 2604 and QWP 2510. similar.

[0263] In various embodiments, one or both of PB L1 2612 and PB L2 2616 may be switchable lenses, which may be switchable, such as by application of an electric field, voltage or current. Also, one or both of PB L1 2612 and PB L2 2616 can have variable focal intensities or focal depths, the focal intensities and focal depths of which are dependent on, for example, application of an electric field, voltage, or current. can be controlled by

[0264] Referring to Fig. 27C, a display device 2700C is used herein to describe outputting a virtual image to a user. As described above with respect to FIG. 25B , a portion of light propagating in the x-direction within one or more waveguides in waveguide assembly 2504 may be redirected or out-coupled in the z-direction. The paths of the light beams out-coupled from the waveguide assembly 2504, including the linearly polarized light beams (2516-V with LVP and 2516-H with LHP), are the light beams 2516-V with LVP and 2520-V) are the same as those described above with respect to FIG. 26C until transmitted through the polarizing notch reflector 2514, eg, a linear polarizing notch reflector. Upon exiting polarization notch reflector 2514, light beams 2516-V and 2520-V are transmitted through QWP 2 2510 and are thus converted to light beams 2516-R and 2520-R with RHCP . Light beams 2516-R and 2520-R with RHCP are then further transmitted through PB L2 2716. When activated, PB L2 focuses or defocuses light beams 2520-R and 2516-R into focused output light beams 2620 prior to viewing by eye 4.

[0265] Referring to FIG. 27D, display device 2700D is used herein to describe outputting an image of world 1114 to a user. As illustrated, incident light beams 2632-R and 2624-L, with RHCP and LHCP, pass through PB L1 2712, through non-polarized notch reflector 2508, and through QWP 1 2604, respectively. transmitted, thereby converting the light beams into linearly polarized light beams. The circularly polarized light beam is further transmitted through the waveguide assembly 2504, a polarizing notch reflector 2514, such as a linearly polarizing notch reflector, and through QWP 2 2510, whereby the light beams have RHCP and LHCP. and back-converted to circularly polarized light beams 2636-R and 2628-L, respectively. Light beams 2636-R and 2628-L are then transmitted through PB L2 2716, thus outputting respective light beams 2632 and 2628, respectively.

[0266] To output a real world image, lenses PB L1 2712 and PB L2 2716 are configured to operate on light having one of the circular polarizations but not the other. Consequently, in the illustrated embodiment, one of the incident light beams 2632-R and 2624-L, e.g., light beam 2624-L with an LHCP, is coupled to the lenses PB L1 2712 and PB L2 2716. ) is not affected by

[0267] PB L1 2712 and PB L2 2716 may be configured to have opposite lensing effects on light passing through them. For example, when PB L1 2712 is configured to have a focusing lens effect, PB L2 2716 can be configured to have a defocusing effect so that opposite lens effects negate each other. Consequently, the image of the world 1114 viewed by eye 4 is substantially unaffected, while the virtual image is affected by PB L2 2716, as described above with respect to FIG. 27C. .

Example Spatial Offset Compensators for Polarization-Sensitive Variable-Focus Lenses

[0268] When a polarization-sensitive lens such as a PB lens is used, the two orthogonally polarized images undergo different optical passes through the lenses. For example, a PB lens may split the world-image into two polarized images with different magnifications (which may lead to double images with a spatial offset between them). This effect is illustrated in Fig. 28A, which illustrates a display device 2800A configured similarly to the display devices 2700A/2700B of Figs. 27A and 27B. As described above, the two PB lenses can be configured to negate each other's lensing effect, but the magnitudes of the two polarized images formed by light beam 2632 with LHCP and light beam 2628 with RHCP Offset 2804 can be maintained as illustrated in FIG. 28A. For example, in FIG. 28A , PB L1 exerts a positive optical force on light beam 2632-R with RHCP, while exerting a negative optical force on light beam 2624-L with LHCP. In the following, various arrangements configured to compensate for the offset 2804 are disclosed.

[0269] FIG. 28B illustrates an offset compensator 2800B comprising a pair of lenses 2804, 2808, eg, a pair of PB lenses. A pair of lenses (PB L3 (2804) and PB L4 (2808)) is such that when incident light beams having RHCP and LHCP are incident on PB L3, PB L3 exerts a positive optical power on a light beam having LHCP. while exerting a negative optical force on the light beam having the RHCP. Thus, the optical forces of PB L3 2804 and PB L4 2808 are opposite to those of PB L1 2612 and PB L2 2716, respectively, so that the spatial offset 2812 is equivalent to the display device 2800A (FIG. 28A). is between output light beams 2632 and 2628 output from offset compensator 2800B, which are opposite in direction and substantially equal in magnitude compared to output light beams 2632 and 2628 output from offset compensator 2800B. Thus, the spatial offset 2804 illustrated in FIG. 28A can be compensated for by placing a pair of lenses that produce an offset 2812 with the same magnitude in opposite directions, as illustrated in FIG. 28B.

[0270] FIG. 28C illustrates a combination of an offset compensator 2800B (FIG. 28B) and a stacked display device 2800A (FIG. 28A). Variable focus lenses of the same type as used in the optics of FIG. 28A may be used to construct the offset compensator. Static lenses can be used when partial compensation is acceptable. As illustrated, the offset can be avoided by placing a polarizer in front of the notch filter (e.g., a linear polarizer for linear LC lenses or a circular polarizer for PB lenses), at the expense of brightness of the world image. Still, virtual images are not affected. Offset compensator 2800B can be placed on the world-ward side of the eyepiece (eg, as shown in FIG. 28C), or on the eye-ward side of the eyepiece (eg, as shown in FIG. 28C). , towards the right where the user's eyes are located). A number of offset compensators may be used.

1182 , 1184 , 1186 , 1188 , 1190 in FIG. 6 , as described above with respect to various display devices, generally in the direction of propagation, e.g. Light propagating in the x-direction is output out of the waveguide, eg, using out-coupling optical elements or light extraction optical elements (eg, 1282, 1284, 1286, 1288, 1290 in FIG. 6), orthogonal Image information may be output in a direction, for example, a z-direction. As described above, various embodiments of out-coupling optical elements may include cholesteric liquid crystal gratings (CLCGs). As light propagates within one or more waveguides (eg, 1182, 1184, 1186, 1188, 1190 in FIG. 6), CLCGs (eg, 1282, 1284, 1286, 1288, 1290 in FIG. couples the light out of the field. Under some configurations of the CLC layers of CLCGs, the out-coupled light can have a substantially uniform polarization state in a single direction, eg the z-direction. For example, the CLC layer(s) of CLCG having chiral structures (eg, 1012-1, 1012-2, ... 1012-i in FIG. 10) in which liquid crystal molecules are rotated in the same direction, for example, clockwise or counterclockwise. ) can out-couple light having a substantially uniform polarization, such as LHCP or RHCP. In these embodiments, since the waveguide assembly 2504 out-couples light having a substantially uniform polarization, a display device comprising the waveguide assembly 2504 including CLCGs is used to convert the polarization of the output light. Some of the optical elements described above may be omitted.

Exemplary Polarizing Eyepieces with Variable-Focus Lenses

[0272] In the following, the eyepiece 1004 preferentially directs light in a particular direction (e.g., right in FIG. 29, towards the eye) compared to other directions (e.g., left in FIG. 29, toward the world). can be projected. Referring to FIG. 29 , a display device 2900 includes a waveguide assembly 2904, and the waveguide assembly 2904 is interposed between first and second PB lenses 2612 and 2616, respectively. Advantageously, in this example, since the light beam 2636-R of the image output from the waveguide assembly 2904 is already polarized (e.g., right circularly polarized or RHCP), an additional polarizer or polarization conversion can be omitted. , because the light projected from eyepiece 1004 is already preferentially in the polarization state acted upon by lens 2616 (RHCP in this example). Thus, a portion of the light propagating under TIR within the waveguide assembly 2904 is caused by DOEs formed therein, e.g., as circularly polarized light beam 2636-R (or in other implementations, linearly polarized light beams). Can be out-coupled. Light beams 2636-R with RHCP travel in the positive z-direction until they hit PB L2 2616 without passing through the polarization notch reflector before being viewed by eye 4, for example. . Eyepiece 1004 can be used for DOEs, metamaterials, holograms designed to project light asymmetrically in a desired direction and (optionally) in a desired polarization state (e.g., to the right with RHCP, in FIG. 29). can include

Exemplary Deformable Mirror Variable-Focus Displays

[0273] In some embodiments, a deformable mirror may be used to create variable focus effects on virtual images when reflected from the mirror. 30 illustrates a display device 3000 configured to output image information to a user using a waveguide assembly 2904 and a deformable mirror 3004. The display device 3000 includes a waveguide assembly 2904, wherein the waveguide assembly 2904 includes a curved or deformable mirror 3004 (to have optical force) and an optional clean-polarizer 3008. intervened between As described with reference to FIG. 29 , the eyepiece 2904 can be configured to project light asymmetrically towards the left side (towards the world) rather than the right side (towards the eye), in this example. . Eyepiece 2904 may include DOEs, metamaterials, holograms, etc. that may preferentially project light in a desired asymmetric direction and/or a desired polarization state (eg, linear or circular). For example, as shown in FIG. 34 , eyepiece 2904 can include a CLC layer or CLCG.

[0274] In operation, as described above with respect to FIG. 29, a portion of the light propagating in the x-direction within one or more waveguides in waveguide assembly 2904 has uniform circular polarization (e.g., RHCP). As light beam 3012 it can be redirected in the z-direction or out-coupled. The waveguide assembly 2904 projects the light beam 3012 of the virtual user's image towards a curved or deformable mirror 3004 (opposite the side of the user's eye 4). In some embodiments, the deformable mirror 3004 is coated with a polarizing reflective layer (eg, multilayer linear polarization reflectors or broadband cholesteric liquid crystal circular polarization reflectors) to out-couple light having a designated polarization, such as CLCG. It reflects light having the same polarization as the ring polarization and allows light from the real world 1114 to be transmitted towards the eye 4 . In some other embodiments, instead of a polarization reflecting layer, the deformable mirror 3004 is designed to reflect light within a narrow bandwidth (Δλ) that matches the virtual image bandwidth of the light out-coupled from the waveguide assembly 2904. It is coated with a notch reflective layer or a CLC reflective layer. In some embodiments, a clean-up polarizer 3008 may optionally be placed as shown in FIG. 30 to remove any ghost images without going through a deformable mirror.

Cholesteric Liquid Crystal Lenses

[0275] As described elsewhere herein (eg, see FIGS. 30 and 34), some display devices direct light toward the world (eg, toward the world 1114 and away from the user's eye 4). an eyepiece configured to project asymmetrically, and then an optical structure (eg, a deformable mirror in FIG. 3004) or the CLC lens of FIG. 34).

[0276] Figures 31A and 31B illustrate a reflective diffractive lens 3100A that may be implemented as part of a display device, where the reflective diffractive lens 3100A serves as a reflective polarizing mirror in a similar manner to transmissive PB LC lenses. It is formed of patterned CLC materials that do. 31A illustrates local orientations of liquid crystal directors (arrows) over a binary Fresnel lens pattern. Thus, CLC lens 3100A may be configured to have an optical power (eg, which may be adjustable by an applied electric field). Embodiments of the CLC lens 3100A can be used as an alternative to the deformable mirror 3004 in the display of FIG. 30, or (e.g., coating or lamination of a CLC lens on the surface of the mirror 3004). can be used to provide additional reflectance or optical power in the display of FIG. 30 (by combining CLC lens 3100A and mirror 3004 via

[0277] Referring to FIG. 31B, a circularly polarized incident light 3012 having a circular polarization (e.g., RHCP) where a lens 3100A corresponds to (e.g., has a handyness equal to) the CLC chirality. When illuminated with , the reflected light 3016 exhibits similar lensing effects to transmissive PB lenses. On the one hand, light with orthogonal polarization (eg, LHCP) is transmitted without interference. Lens 3100A may be configured to have a bandwidth in the range of less than about 10 nm, less than about 25 nm, less than about 50 nm, less than about 100 nm, or some other range.

[0278] FIG. 31C illustrates a reflective diffractive lens 3100C comprising a plurality of reflective diffractive lenses 3100-R, 3100-G and 3100-B. In the illustrated embodiment, the reflective diffractive lenses 3100-R, 3100-G and 3100-B are in a stacked configuration and are configured to reflect light within a range of wavelengths (Δλ) within the red, green and blue spectra, respectively. do. Lens 3100C is illuminated with circularly polarized incident light 3012 having a circular polarization (e.g., RHCP) corresponding to a wavelength within a range of wavelengths (Δλ) in the red, green, and blue spectra and a handyness of CLC chirality. , the reflected light 3016 exhibits lens effects similar to those of a transmissive PB lens. On the one hand, light with orthogonal polarization (eg, LHCP) is transmitted without interference.

[0279] Because the focal length 3204 varies depending on the wavelength of light, diffractive lenses (eg, Fresnel lenses) often suffer from severe chromatic aberration. This is illustrated in FIG. 32A with respect to diffractive lens 3200A, which shows that incident red, green and blue light is focused at different distances with diffractive lens 3200A.

[0280] Thanks to the moderate bandwidth of CLC materials, a stack of lenses can be implemented with substantially the same focal length for different colors. 32B shows a reflective diffractive lens 3200B comprising a plurality of reflective diffractive lenses 3200-R, 3200-G and 3200-B in a stacked configuration similar to the reflective diffractive lens 3100C illustrated with respect to FIG. 31C. exemplify As shown in FIG. 32B, three individual lenses 3200-R, 3200-G and 3200-B are designed to have substantially the same focal length or optical power for red, green and blue wavelengths, respectively. . Since the bandwidth of CLC materials is about 50 nm to 100 nm in many implementations, cross-talk between the three wavelengths can be reduced or minimized. Although three CLC layers are shown, fewer or more layers corresponding to the colors of light incident on lens 3200B may be used.

Exemplary Dynamic Switching Between CLC Lenses

[0281] FIG. 33A illustrates a reflective diffractive lens assembly 3300 configured for dynamic switching between different focal lengths. Dynamic switching comprises a plurality of reflective diffractive lens sub-assemblies 3300-1, 3300-2 and 3300-3 including first, second and third multi-layer diffractive lenses CLC L1, CLC L2 and CLC L3. , where each of the multi-layer diffractive lenses CLC L1, CLC L2 and CLC L3 includes a plurality of lenses 3100-R, 3100-G and 3100-B. As configured, reflective diffractive lens sub-assemblies 3300-1, 3300-2 and 3300-3 are configured to have different focal lengths. The plurality of reflective diffractive lens sub-assemblies 3300-1, 3300-2 and 3300-3 are coupled to first, second and third switchable half-wave plates HWP1, HWP2 and HWP3 (e.g., switchable LC half-wave plates) are included. In the illustrated embodiment, reflective diffractive lens sub-assemblies 3300-1, 3300-2 and 3300-3 are multi-layer diffractive lenses of sub-assemblies 3300-1, 3300-2 and 3300-3. (CLC L1, CLC L2 and CLC L3) is a stacked configuration made to alternate with switchable half-wave plates (HWP) of sub-assemblies 3300-1, 3300-2 and 3300-3.

[0282] Figures 33B and 33C illustrate an exemplary switching operation between two different reflective diffractive lens sub-assemblies 3300-1 and 3300-2 by modulating the HWPs disposed on each. When the first HWP (HWP1) is in an off-state (eg, no retardation), the light is reflected by the first CLC lens (CLC L1) and the image focus is determined by the first CLC L1. When both HWP1 and HWP2 are on (e.g. half-wave retardation), light is not reflected from CLC L1 when its polarization goes from orthogonal (e.g. LHCP) to operating polarization (e.g. RHCP) . The polarization state is restored by HWP2 and light is reflected from CLC L2. Image focus is now determined by CLC L2.

[0283] Likewise, three different focal lengths can be implemented by adding an additional pair of CLC lenses and HWP as shown in FIG. 33D. Light polarization is converted by HWP1 from orthogonal polarization (eg LCHP) to operating polarization (eg RHCP). Since HWP2 is in the off state, polarization is unaffected and light propagates through CLC L2 without interference. After HWP3, the polarization is flipped again, becoming the operating polarization (e.g., RHCP) and the light is reflected by CLC L3. Image focus is now determined by CLC L3 as shown in FIG. 33D.

[0284] In embodiments, variable focus of virtual images may be implemented by coupling a waveguide assembly 3404 (and also a CLC lens 3408) as illustrated in FIG. 34 . CLC lens 3408 may include any of the embodiments of CLC lenses 3100A, 3100C, 3200A, 3200B, 3300 described herein. Because images projected from the waveguide assembly 3404 propagate preferentially toward the CLC lens (e.g., toward the world, away from the user's eyes) with uniform circular polarization, the image focus is as described above. It can be controlled by CLC lenses. The CLC lens 3408 can include multiple depth planes (eg, DoF1-DoF3 shown in FIG. 33A) and is dynamically switchable as described with reference to FIGS. 33B-33D. When a color-sequential display is used to create virtual images, the waveplates in the CLC lenses need to be modulated synchronously with the working colors projected by the eyepiece 3404. As described above, the CLC lens 3408 can be used alone or in combination with a deformable mirror (eg, mirror 3004) to provide a variable focus display device for virtual images.

additional aspects

[0285] In a first aspect, a display device includes a waveguide configured to propagate visible light under total internal reflection in a direction parallel to a major surface of the waveguide. An outcoupling element is formed on the waveguide and is configured to outcouple a portion of visible light in a direction perpendicular to a major surface of the waveguide. A polarization-selective notch reflector is disposed on a first side of the waveguide and is configured to transmit visible light having a second polarization while reflecting visible light having a first polarization. A polarization-independent notch reflector is disposed on the second side of the waveguide and is configured to reflect visible light having a first polarization and visible light having a second polarization, wherein the polarization-independent notch reflector is configured to convert the polarization of visible light reflected therefrom. It consists of

[0286] In a second aspect, in the display device of the first aspect, each of the polarization-selective notch reflector and the polarization-independent notch reflector transmits light having a wavelength outside the range of wavelengths while transmitting one of red, green, or blue light. It is configured to reflect visible light having a wavelength in the corresponding wavelength range.

[0287] In a third aspect, the display device of the first or second aspect, wherein the polarization-selective notch reflector includes one or more cholesteric liquid crystal (CLC) layers.

[0288] In a fourth aspect, the display device of any one of the first to third aspects, wherein each of the one or more CLC layers includes a plurality of chiral structures, and each of the chiral structures comprises a layer by at least a helical pitch. It includes a plurality of liquid crystal molecules extending in the depth direction and continuously rotating in the first rotation direction. The helical pitch is a length in a layer depth direction corresponding to a net rotation angle of liquid crystal molecules of chiral structures by one full rotation in the first rotation direction. The arrangements of liquid crystal molecules of chiral structures are periodically fluctuated in the lateral direction perpendicular to the layer depth direction.

[0289] In a fifth aspect, the display device of any one of the first to fourth aspects, wherein the first polarization is a first circular polarization and the second polarization is a second circular polarization.

[0290] In a sixth aspect, in the display device of any one of the first to fifth aspects, the display device further includes a first quarter-wave plate and a second quarter-wave plate; A polarization-independent notch reflector is interposed between the first quarter-wave plate and the waveguide, and a polarization-selective notch reflector is interposed between the waveguide and the second quarter-wave plate.

[0291] In a seventh aspect, in the display device of the sixth aspect, the display device further includes a first linear polarization lens and a second linear polarization lens, and the first quarter-wave plate comprises the first linear polarization lens. and the polarization-independent notch reflector, and the second quarter-wave plate is interposed between the polarization-selective notch reflector and the second linear polarization lens.

[0292] In an eighth aspect, the display device of any one of the first to fourth aspects, wherein the display device comprises a first PB disposed on outer sides of the polarization-independent notch reflector and the polarization-selective notch reflector ( A Pancharatnam-Berry) lens and a second Pancharatnam-Berry (PB) lens are further included.

[0293] In a ninth aspect, in the display device of the first aspect or the second aspect, the display device further includes a first quarter-wave plate interposed between the polarization-independent notch reflector and the waveguide.

[0294] In a tenth aspect, the display device of the ninth aspect, wherein the display device further comprises a second quarter-wave plate, and the polarization-independent notch reflector comprises the first quarter-wave plate and the second quarter-wave plate. It is interposed between the 1/4-wave plates.

[0295] In an eleventh aspect, the display device of the tenth aspect, wherein the display device further comprises a first linearly polarized lens and a second linearly polarized lens, wherein the first quarter-wave plate is the first linearly polarized lens and a polarization-independent notch reflector, and a polarization-selective notch reflector is interposed between the waveguide and the second linear polarization lens.

[0296] In a twelfth aspect, the display device of the ninth aspect, wherein the display device comprises a second PB (Pancharatnam-Berry) lens disposed on outer sides of the polarization-independent notch reflector and the polarization-selective notch reflector. It further includes a Pancharatnam-Berry (PB) lens and a second quarter-wave plate interposed between the second PB lens and the polarization-selective notch reflector.

[0297] In a thirteenth aspect, the display device includes a wave-guiding device interposed between the first switchable lens and the second switchable lens. The optical waveguide device includes one or more cholesteric liquid crystal (CLC) layers each including a plurality of chiral structures, each chiral structure extending in a layer depth direction and continuously rotating in a first rotation direction. of liquid crystal molecules, and arrangements of liquid crystal molecules of chiral structures are periodically fluctuated in a lateral direction perpendicular to the layer depth direction, so that one or more CLC layers are configured to Bragg-reflect incident light. One or more waveguides are formed over the one or more CLC layers and configured to propagate visible light under total internal reflection (TIR) in a direction parallel to a major surface of the waveguide and optically couple visible light to or from the one or more CLC layers.

[0298] In a 14th aspect, the display device of the 13th aspect, wherein one or more waveguides are interposed between the polarization-selective notch reflector and the polarization-independent notch reflector, the polarization-selective notch reflector emitting visible light having a first polarization. configured to transmit visible light having a second polarization while reflecting, the polarization-independent notch reflector configured to reflect visible light having the first polarization and visible light having the second polarization.

[0299] In a fifteenth aspect, the display device of the thirteenth aspect, wherein the one or more CLC layers serve as a polarization-selective notch reflector.

[0300] In a sixteenth aspect, the display device of the thirteenth aspect, wherein the polarization-selective notch reflector includes one or more cholesteric liquid crystal (CLC) layers.

[0301] In a seventeenth aspect, the display device of the sixteenth aspect, wherein each of the one or more CLC layers includes a plurality of chiral structures, each of the chiral structures extending in a layer depth direction by at least a helical pitch and having a first rotation It includes a plurality of liquid crystal molecules continuously rotated in the direction. The helical pitch is a length in a layer depth direction corresponding to a net rotation angle of liquid crystal molecules of chiral structures by one full rotation in the first rotation direction. The arrangements of liquid crystal molecules of chiral structures are periodically fluctuated in the lateral direction perpendicular to the layer depth direction.

[0302] In an eighteenth aspect, the display device of any one of aspects thirteenth through seventeenth, wherein the polarization-selective notch reflector is configured to preserve polarization of visible light reflected therefrom, and the polarization-independent notch reflector is configured from configured to convert the polarization of reflected visible light.

[0303] In a nineteenth aspect, the display device of any one of aspects thirteenth to eighteenth, wherein the first switchable lens and the second switchable lens have optical powers having opposite signs when activated.

[0304] In a twentieth aspect, the display device of any one of the thirteenth to nineteenth aspects, wherein the first switchable lens comprises a Pancharatnam-Berry (PB) lens and the second switchable lens comprises a second PB (Pancharatnam-Berry) lenses.

[0305] In a 21st aspect, the display device of any one of the 13th to 20th aspects, wherein the display device further comprises a first quarter-wave plate interposed between the polarization-independent notch reflector and the waveguide. do.

[0306] In a 22nd aspect, the display device of any one of aspects 13-21, wherein the display device is interposed between the second switchable lens and the polarization-selective notch reflector. Including more plates.

[0307] In a twenty-third aspect, a display device configured to display an image to a user's eye includes an optical display comprising an anterior side and a posterior side, the posterior side being closer to the user's eye than the anterior side, the optical display comprising: It is configured to output light having a wavelength range towards the rear side. A first notch reflector is disposed behind the optical display, and the first notch reflector is configured to reflect light having a range of wavelengths output from the optical display. A second notch reflector is disposed in front of the optical display, and the second notch reflector is configured to reflect light having a range of wavelengths. The first notch reflector is configured to substantially transmit light having a first polarization and substantially reflect light having a second polarization different from the first polarization. The second notch reflector is configured to convert light having a second polarization incident on the rear face to a first polarization and redirect the light backward.

[0308] In a twenty-fourth aspect, in the display device of the twenty-third aspect, the first notch reflector includes a cholesteric liquid crystal (CLC) grating (CLCG).

[0309] In a twenty-fifth aspect, the display device of the twenty-third aspect, wherein the first notch reflector comprises multiple layers and the second notch reflector comprises a non-polarizing notch reflector and a quarter-wave plate.

[0310] In the 26th aspect, the display device of any one of the 23rd to 25th aspects, wherein the display device is in front of the first variable focus lens disposed behind the first notch reflector and the second notch reflector. It further includes an disposed second variable focus lens, wherein second optical characteristics of the second variable focus lens compensate for first optical characteristics of the first variable focus lens.

[0311] In a twenty-seventh aspect, in the display device of the twenty-sixth aspect, each of the first variable focus lens and the second variable focus lens includes a linear polarization lens.

[0312] In a twenty-eighth aspect, in the display device of the twenty-sixth aspect, each of the first variable focus lens and the second variable focus lens includes a Pancharatnam-Berry (PB) phase lens.

[0313] In a twenty-ninth aspect, the display device of the twenty-eighth aspect, wherein the display device further comprises a spatial offset compensator configured to compensate for spatial offset introduced by the PB phase lenses.

[0314] In a thirtieth aspect, a dynamically focused display system includes a display configured to output circularly polarized light in a first circular polarization state. The display is disposed along an optical axis and has a front side and a back side, the back side being closer to the user's eye than the front side, and the optical display is configured to output light having a range of wavelengths towards the back side. A first switchable optical element is disposed in front of the first CLC lens along an optical axis, and the first switchable optical element converts a circular polarization state of light transmitted through the first switchable optical element from the first circular polarization state. and change to a second, different circular polarization state. A first cholesteric liquid crystal (CLC) lens is disposed in front of the first switchable optical element along an optical axis. A second switchable optical element is disposed in front of the first CLC lens along an optical axis, and the second switchable optical element converts a circular polarization state of light transmitted through the second switchable optical element to the first circular polarization state. to a second, different circular polarization state. A second CLC lens is disposed in front of the second switchable optical element along the optical axis. The controller is configured to electronically switch states of the first and second switchable optical elements to dynamically select the first CLC lens or the second CLC lens.

[0315] In a 31 aspect, the dynamically focused display system of the 30th aspect, in response to selection of the first CLC lens, the first switchable optical element is configured to allow transmission of light having a first polarization state. is switched In response to selection of the second CLC lens, the first switchable optical element is switched to change the polarization of light from the first circular polarization state to the second circular polarization state, the second switchable optical element to the second circular polarization state. to change the polarization of light from to the first circular polarization state.

[0316] In a 32nd aspect, the dynamically focused display system of the 30th or 31st aspect, the first and second switchable optical elements include half-wave plates.

[0317] In a thirty-third aspect, a wearable augmented reality display system includes the dynamically focused display system of any of the thirty-second aspects.

[0318] In a thirty-fourth aspect, a wearable augmented reality head-mounted display system is configured to direct light from the world in front of a wearer wearing the head-mounted system to eyes of the wearer. A wearable augmented reality head mounted display system includes an optical display configured to output light to form an image; one or more waveguides positioned to receive the light from the display; a frame configured to place waveguides in front of the eye such that the one or more waveguides have an anterior side and a posterior side, the posterior side being closer to the eye than the anterior side; a cholesteric liquid crystal (CLC) reflector disposed on the front side of the one or more waveguides, wherein the CLC reflector is configured to have an adjustable optical power or depth of focus upon application of an electrical signal; and one or more out-coupling elements disposed relative to the one or more waveguides for extracting light from the one or more waveguides and directing at least a portion of the light propagating within the waveguide to a CLC reflector, the light comprising: Directed back from the CLC reflector through the waveguide and to the eye to present an image from the display to the eye of the wearer.

[0319] In a thirty-fifth aspect, a display device includes a waveguide configured to propagate visible light under total internal reflection in a direction parallel to a major surface of the waveguide and outcouple visible light in a direction perpendicular to the major surface. The notch reflector is configured to reflect visible light having a first polarization, the notch reflector includes one or more cholesteric liquid crystal (CLC) layers, each of the CLC layers includes a plurality of chiral structures, each of the chiral structures has a layer depth. direction and continuously rotated in the first rotation direction, the arrangements of the liquid crystal molecules of chiral structures are periodically fluctuated in the lateral direction perpendicular to the layer depth direction, so that one or more CLC layers reflect incident light. Be configured to be Bragg-reflect.

[0320] In a 36 aspect, the display device of the 35 aspect, wherein the waveguide is configured to selectively outcouple visible light towards the notch reflector.

[0321] In a 37 aspect, the display device of the 35 or 36 aspect, wherein the notch reflector includes a deformable mirror on which one or more CLC layers are formed (or disposed).

[0322] In a 38 aspect, the display device of any one of aspects 35 to 37, wherein different CLC layers of the one or more CLC layers transmit wavelengths in a wavelength range corresponding to different ones of the red, green or blue light. It is configured to reflect visible light having a wavelength, while being configured to transmit light having a wavelength outside the wavelength range.

[0323] In the 39th aspect, the display device of any one of the 35th to 38th aspects, wherein each of the chiral structures of the CLC layers includes a plurality of liquid crystal molecules extending in the layer depth direction by at least a helical pitch. and different CLC layers of the one or more CLC layers have different helical pitches.

[0324] In a fortieth aspect, the display device of the thirty-eighth or thirty-ninth aspect, different CLC layers of the one or more CLC layers have substantially the same optical power.

[0325] In a 41st aspect, the display device of any one of aspects 35-40, wherein the display device includes a plurality of notch reflectors, each of the notch reflectors configured to reflect visible light having a first polarization. wherein each of the notch reflectors includes one or more cholesteric liquid crystal (CLC) layers, each of the CLC layers includes a plurality of chiral structures, and each of the chiral structures extends in a layer depth direction and is continuous in a first rotational direction. , and arrangements of liquid crystal molecules of chiral structures are periodically fluctuated in a lateral direction perpendicular to the layer depth direction, so that one or more CLC layers are configured to Bragg-reflect incident light. let it be

[0326] In a 42nd aspect, the display device of any of aspects 35-41, different notch reflectors of the notch reflectors have different optical powers.

[0327] In a 43rd aspect, in the display device of the 41st or 42nd aspect, the display device further includes a half-wave plate corresponding to each of the notch reflectors.

Additional Considerations

[0328] In the embodiments described above, augmented reality display systems, and more specifically, spatially varying diffraction gratings, are described with respect to specific embodiments. However, it will be appreciated that the principles and advantages of the embodiments may be used in any other systems, apparatus or methods having a need for a spatially varying diffraction grating. From the above, it will be appreciated that any feature of any one of the embodiments may be combined with and/or substituted with any other feature of any other of the embodiments.

[0329] Throughout the specification and claims, unless the context clearly requires otherwise, words such as "comprise, include" and "comprising, including" have the exclusive or exhaustive meaning. In contrast, it is interpreted in an inclusive sense; That is, it is interpreted as meaning "including (but not limited to)". The word “coupled” as generally used herein refers to two or more elements that may be directly connected or connected by one or more intermediate elements. Likewise, the word “connected” as generally used herein refers to two or more elements that may be directly connected or connected by one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” “below,” “above,” and words of similar meaning, when used herein, refer to any particular portion of this application. should refer to the application as a whole, and not to the Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number, respectively. The word "or" in reference to a list of two or more items covers all of the following interpretations of the word: any of the items in the list, all items in the list, any combination of one or more of the items in the list. do. Also, as used in this specification and the appended claims, the terms "a" and "an" shall be construed to mean "one or more" or "at least one" unless otherwise specified.

[0330] As used herein, a phrase referring to "at least one of" the items of a list refers to any combination of those items, including single members. By way of example, “at least one of A, B or C” means A; B; C; A and B; A and C; B and C; and intended to cover A and B and C. Unless specifically stated otherwise, a conjunction such as the phrase “at least one of X, Y, or Z” is otherwise in a context commonly used to convey that an item, term, etc., may be at least one of X, Y, or Z. I understand. Accordingly, such conjunctions are generally not intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z, respectively.

[0179] Moreover, unless specifically stated otherwise or otherwise understood within the context of use, the conditional terms used herein such as, among other things, "can, could, might, may", “For example,” “such as,” “such as,” etc. are generally intended to convey that certain embodiments include certain features, elements, and/or states that other embodiments do not. Accordingly, such a conditional generally indicates that features, elements, and/or states are in some way required for one or more embodiments, or that those features, elements, and/or states are required in any particular embodiment. It is not intended to imply that it is included in or performed in any particular embodiments.

[0180] Although certain embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present disclosure. Indeed, the novel apparatus, methods and systems described herein may be embodied in a variety of different forms; Furthermore, various omissions, substitutions, and changes in the form of the methods and systems described herein may be made without departing from the spirit of the present disclosure. For example, while blocks are presented in a given arrangement, alternative embodiments may perform similar functionalities with different components and/or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and/or modified. can Each of these blocks can be implemented in a variety of different ways. Any suitable combination of elements and acts of the various embodiments described above may be combined to provide additional embodiments. The various features and processes described above may be implemented independently of each other, or may be combined in various ways. No element or combination of elements is essential or indispensable for all embodiments. All suitable combinations and subcombinations of the features of this disclosure are intended to fall within the scope of this disclosure.

Claims (10)

A display device comprising a wave-guiding device interposed between a first switchable lens assembly and a second switchable lens assembly,
The light-waveguide device,
one or more cholesteric liquid crystal (CLC) layers each comprising a plurality of chiral structures; and
one or more waveguides formed over the one or more CLC layers;
Each chiral structure includes a plurality of liquid crystal molecules extending in a layer depth direction and successively rotated in a first rotation direction, and arrangements of the liquid crystal molecules of the chiral structures periodically fluctuate in a lateral direction perpendicular to the layer depth direction. so that the one or more CLC layers are configured to Bragg-reflect incident light;
the one or more waveguides to propagate visible light by total internal reflection (TIR) in a direction parallel to a major surface of the waveguide and to optically couple visible light to or from the one or more CLC layers; made up,
display device. According to claim 1,
the one or more waveguides are interposed between a polarization-selective notch reflector and a polarization-independent notch reflector;
the polarization-selective notch reflector is configured to transmit visible light having a second polarization while reflecting visible light having a first polarization;
wherein the polarization-independent notch reflector is configured to reflect visible light having the first polarization and visible light having the second polarization,
display device. According to claim 2,
wherein the one or more CLC layers function as the polarization-selective notch reflector;
display device. According to claim 2,
wherein the polarization-selective notch reflector comprises one or more CLC layers;
display device. According to claim 4,
each of the one or more CLC layers of the polarization-selective notch reflector includes a plurality of chiral structures;
Each of the chiral structures includes a plurality of liquid crystal molecules extending in a layer depth direction by at least a helical pitch and continuously rotated in a first rotation direction;
The helical pitch is a length in the layer depth direction corresponding to a net rotation angle of liquid crystal molecules of the chiral structures by one full rotation in the first rotation direction,
The arrangements of the liquid crystal molecules of the chiral structures are periodically fluctuated in a lateral direction perpendicular to the layer depth direction,
display device. According to claim 2,
the polarization-selective notch reflector is configured to preserve polarization of visible light reflecting from the polarization-selective notch reflector;
The polarization-independent notch reflector is configured to convert the polarization of visible light reflecting from the polarization-independent notch reflector.
display device. According to claim 2,
Further comprising a first quarter-wave plate interposed between the polarization-independent notch reflector and the waveguide.
display device. According to claim 7,
Further comprising a second quarter-wave plate interposed between the second switchable lens and the polarization-selective notch reflector.
display device. According to claim 1,
wherein the first switchable lens and the second switchable lens have optical powers having opposite signs when activated.
display device. According to claim 1,
The first switchable lens assembly includes a Pancharatnam-Berry (PB) lens, and the second switchable lens assembly includes a second Pancharatnam-Berry (PB) lens.
display device.